Perspectives in Diabetes

Hypomagnesemia in Type 2 Diabetes: A Vicious Circle?

  1. Lisanne M.M. Gommers1,
  2. Joost G.J. Hoenderop1,
  3. René J.M. Bindels1 and
  4. Jeroen H.F. de Baaij1,2⇑
  1. 1Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands
  2. 2Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
  1. Corresponding author: Jeroen H.F. de Baaij, jeroen.debaaij{at}radboudumc.nl.
Diabetes 2016 Jan; 65(1): 3-13. https://doi.org/10.2337/db15-1028

Abstract

Over the past decades, hypomagnesemia (serum Mg2+ <0.7 mmol/L) has been strongly associated with type 2 diabetes mellitus (T2DM). Patients with hypomagnesemia show a more rapid disease progression and have an increased risk for diabetes complications. Clinical studies demonstrate that T2DM patients with hypomagnesemia have reduced pancreatic β-cell activity and are more insulin resistant. Moreover, dietary Mg2+ supplementation for patients with T2DM improves glucose metabolism and insulin sensitivity. Intracellular Mg2+ regulates glucokinase, KATP channels, and L-type Ca2+ channels in pancreatic β-cells, preceding insulin secretion. Moreover, insulin receptor autophosphorylation is dependent on intracellular Mg2+ concentrations, making Mg2+ a direct factor in the development of insulin resistance. Conversely, insulin is an important regulator of Mg2+ homeostasis. In the kidney, insulin activates the renal Mg2+ channel transient receptor potential melastatin type 6 that determines the final urinary Mg2+ excretion. Consequently, patients with T2DM and hypomagnesemia enter a vicious circle in which hypomagnesemia causes insulin resistance and insulin resistance reduces serum Mg2+ concentrations. This Perspective provides a systematic overview of the molecular mechanisms underlying the effects of Mg2+ on insulin secretion and insulin signaling. In addition to providing a review of current knowledge, we provide novel directions for future research and identify previously neglected contributors to hypomagnesemia in T2DM.

Introduction

Globally, over 300 million people suffer from type 2 diabetes mellitus (T2DM), and the prevalence is predicted to rise to over 600 million over the next decades (1). T2DM is characterized by a combination of insulin deficiency and insulin resistance. The general pathophysiological concept is that hyperglycemia emerges when endogenous insulin secretion can no longer match the increased demand owing to insulin resistance (2).

Since the 1940s, it has been reported that T2DM is associated with hypomagnesemia (3,4). Low serum magnesium (Mg2+) levels have been reported in large cohorts of patients with T2DM (5). In T2DM, the prevalence of hypomagnesemia ranges between 14 and 48% compared with between 2.5 and 15% in healthy control subjects (4). Hypomagnesemia is associated with a more rapid, and permanent, decline in renal function in patients with T2DM (6). In addition, epidemiological studies consistently show an inverse relationship between dietary Mg2+ intake and risk of developing T2DM (7). Several patient studies have shown beneficial effects of Mg2+ supplementation on glucose metabolism and insulin sensitivity (8–10). Recently, Rodríguez-Morán et al. (11) published an excellent overview of the clinical studies addressing the role of Mg2+ in T2DM. In our review, we will focus on the molecular mechanisms underlying these clinical observations.

Mg2+ is an essential ion for human health, as it is involved in virtually every mechanism in the cell, including energy homeostasis, protein synthesis, and DNA stability (12). Considering these divergent functions, it can be appreciated that serum Mg2+ levels are tightly regulated between 0.7 and 1.05 mmol/L in healthy individuals. However, impaired intestinal Mg2+ absorption or renal Mg2+ wasting can lead to hypomagnesemia. A wide range of genetic and environmental factors can affect the Mg2+-deficient state, which have previously been extensively reviewed (12).

In this review, we address the following questions that are central to the role of hypomagnesemia in T2DM: 1) Does Mg2+ regulate insulin secretion? 2) How does Mg2+ affect insulin resistance? 3) How does insulin regulate Mg2+ homeostasis? Taken together, these questions will aid the understanding of whether hypomagnesemia is a causative factor for or a consequence of T2DM.

Insulin Resistance

Insulin Sensitivity in Normal Cell Physiology

Increased insulin resistance is the major pathophysiological cause for the development of T2DM. In healthy subjects, insulin increases glycogen production in the liver, lipid synthesis by adipose tissue, and glucose uptake in muscle (5,13–18). Insulin resistance is often the consequence of reduced sensitivity of the insulin receptor that is composed of two insulin-binding α-subunits and two β-subunits. Specifically, upon insulin binding, the tyrosine residues of the β-subunits become autophosphorylated, activating a wide signaling network in the cell (Fig. 1). Depending on the target tissue, direct substrates of the insulin receptor may be recruited to the receptor, of which insulin receptor substrates (IRSs)-1–4 are the most studied. These IRSs, in turn, phosphorylate downstream signaling pathways leading to glucose uptake, glycogenesis, lipid synthesis, and other insulin-dependent actions. Alternatively, the insulin receptor can activate IRS-independent pathways via Src homology 2 domain containing transforming protein causing the activation of mitogen-activated protein kinase signaling and regulation of cell proliferation (16,19). An overview of the main insulin signaling pathways is provided in Fig. 1.

Figure 1
Figure 1

Mg2+ affects insulin sensitivity. Mg2+ regulates the insulin signaling pathway by increasing the affinity of the insulin receptor tyrosine kinase for ATP. Consequently, hypomagnesemia is associated with a reduced activity of all downstream pathways. In the muscle, Mg2+ therefore regulates the membrane trafficking of GLUT4. In the liver, Mg2+ is an important regulator of enzymes in gluconeogenesis, including G6Pase and PEPCK. In adipose tissue, Mg2+ acts as an anti-inflammatory factor reducing IL-1 and TNF-α secretion. FOXO1, forkhead box class O1; Grb2, growth factor receptor-bound protein 2; GSK3, glycogen synthase kinase 3; MEK/MAPK, mitogen-activated protein kinase kinase; P, phosphorylation; PIP3, phosphatidylinositol 3,4,5 trisphosphate; PI3K, phosphatidylinositol 3-kinase; PKC, protein kinase C; ROS, reactive oxygen species; Shc, Src homology 2 domain containing transforming protein.

Role of Mg2+ in Insulin Sensitivity

Many clinical studies have shown that hypomagnesemia is associated with increased insulin resistance in T2DM patients (4,20–22). In a cross-sectional study of patients with metabolic syndrome, it was shown that insulin resistance associates with reduced serum Mg2+ levels (21). Furthermore, a cohort study of adult black Americans showed that Mg2+ deficiency contributes to an insulin-resistant state (20). Similar results were found in healthy human subjects, where induced Mg2+ deficiency reduced insulin action and secretion (22). In this segment of the review, we will clarify the association between hypomagnesemia and insulin resistance by focusing on the effects of Mg2+ on the insulin receptor activity and downstream signaling events.

Insulin Receptor Phosphorylation

It is widely accepted that Mg2+ is essential for autophosphorylation of the β-subunits of the insulin receptor. The crystal structure of the insulin receptor tyrosine kinase shows that two Mg2+ ions can bind to the tyrosine kinase domain (23). The role of this Mg2+ binding has been shown by in vitro studies using isolated insulin receptors. Here, Mg2+ enhances tyrosine kinase activity by increasing the receptor’s affinity for ATP (24,25). Indeed, rats with hypomagnesemia have reduced levels of insulin receptor phosphorylation, mimicking a state of insulin resistance (26,27). In contrast, increased insulin receptor phosphorylation was shown in liver tissue of rats fed Mg2+-deficient diets for 11 weeks (28). However, the value of this study can be questioned because insulin phosphorylation was normal in rats with the same serum Mg2+ levels at 6 weeks or in muscle tissue. Altogether, Mg2+ seems to be an important factor in insulin receptor autophosphorylation. Defective insulin receptor phosphorylation is therefore regarded as the main mechanism by which hypomagnesemia contributes to insulin resistance in T2DM patients.

Glucose Metabolism in the Muscle

Glucose uptake in skeletal muscle accounts for the disposal of ∼80% of the dietary glucose load via insulin-dependent glucose uptake using GLUT4 glucose transporters (29). In a recent study in rats with streptozotocin (STZ)-induced diabetes, oral Mg2+ supplementation increased GLUT4 expression in the rat muscle and thereby lowered serum glucose levels to the normal range (30). Similar results were obtained in STZ mice treated with Mg2+-rich sea water, showing increased GLUT1 and GLUT4 expression in muscle (31). Although the molecular mechanism is still unknown, these findings suggest that Mg2+ regulates glucose uptake in muscle.

Glycogen Synthesis in the Liver

Although many enzymes in the liver require Mg2+ for their activity, the role of Mg2+ in gluconeogenesis and glycogenesis is poorly studied. The activity of several enzymes involved in gluconeogenesis including glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) were measured in Mg2+-deficient rats, but only PEPCK activity was increased (32). In the same vein, mice with STZ-induced diabetes showed decreased PEPCK and G6Pase mRNA expression when supplemented with Mg2+-rich deep sea water (31). However, it cannot be excluded that other molecules that are present in the sea water mediate these effects. In contrast, mRNA expression of PEPCK was decreased in Mg2+-deficient rats (33).

Obesity and Inflammatory Aspects

Obesity is a major risk factor for the development of T2DM (16,34). In obese patients with T2DM, adipocytes produce proinflammatory mediators, such as interleukin 1 (IL-1) and tumor necrosis factor-α (TNF-α), and stimulate the production of reactive oxygen species. The inflammatory environment is regarded as an important contributor to insulin resistance and is one of the main reasons that obesity is associated with T2DM (15,16). Among others, chronic inflammation may induce insulin resistance by reducing GLUT4 activity and inhibiting IRS-1 action (reviewed in 35).

Mg2+ is an important anti-inflammatory molecule, and therefore hypomagnesemia increases the inflammatory environment in obesity. IL-1 and TNF-α are significantly increased in Mg2+-deficient hamsters and rats (36). Moreover, low serum Mg2+ levels are associated with increased levels of TNF-α in obese people without diabetes (37). Additionally, Mg2+ deficiency contributes to neutrophil activation and oxidative stress (38). In a community-based cross-sectional study of 488 healthy children, an inverse correlation between serum Mg2+ levels and hs-CRP was demonstrated (39). A recent clinical randomized double-blind placebo-controlled trial of healthy subjects with prediabetes and hypomagnesemia showed reduced hs-CRP levels after Mg2+ supplementation for 3 months (40). Given that inflammation and oxidative stress are important factors in the development of insulin resistance (35,41), hypomagnesemia may cause increased insulin resistance.

Novel Perspectives

Although there is extensive evidence that hypomagnesemia reduces insulin receptor phosphorylation and increases chronic inflammation in T2DM patients, the consequences of these signaling events in affected tissues, such as muscle, liver, and adipocytes, have barely been studied. For instance, Ca2+ has been shown to increase glucose uptake via GLUT4 in the skeletal muscle (42). Given that Mg2+ is an antagonist of Ca2+, GLUT4 membrane trafficking may be reduced in hypomagnesemia. Additionally, some early studies suggest that Mg2+ may affect adipokine levels (43). Therefore, future research should be aimed at identifying the effects of hypomagnesemia in target tissues, taking into account the intrinsic effects of Mg2+ on gene expression and Ca2+ antagonism.

Insulin Secretion

Insulin Secretion in Normal Cell Physiology

Acute insulin secretion from pancreatic β-cells is essential to the control of blood glucose homeostasis. Increased blood glucose levels stimulate the influx of glucose in pancreatic β-cells via GLUT2, where it is converted to glucose-6-phosphate (G6P) by glucokinase (44). This enzymatic reaction functions as a glucose sensor to determine the required amount of insulin secretion. G6P is further metabolized by glycolysis to generate ATP, which directly induces closure of KATP channel Kir6.2 (45). Closure of these channels induces depolarization of the plasma membrane and, consequently, opening of voltage-dependent Ca2+ channels (46). The influx of extracellular Ca2+ triggers the release of insulin via exocytosis (19) (Fig. 2).

Figure 2
Figure 2

Mg2+ regulates insulin secretion in pancreatic β-cells. In pancreatic β-cells, Mg2+ directly influences the rate of glucokinase activity by acting as a cofactor for adenine nucleotides. The product of this enzymatic reaction, G6P, is further processed in glycolysis producing ATP. Closure of the KATP channel is dependent on ATP by its binding to the Kir6.2 subunits. Conversely, MgATP initiates channel opening by binding to the SUR1 subunits of the channel. Importantly, the physiological consequence of channel closure is the depolarization of the membrane, which triggers the influx of Ca2+ via the L-type Ca2+ channels. This final step initiates insulin vesicle release, which is negatively controlled by Mg2+ acting on both Ca2+ influx and the L-type Ca2+ channels.

In the early phases of T2DM, insulin release meets the increasing demands by expanding the pancreatic β-cell mass (47). For decades, insulin resistance was thought to be the major cause for T2DM. However, supported by genome-wide association studies studies, evidence has accumulated that impaired insulin secretion in the pancreatic β-cells is a major contributor to the development of T2DM (48,49).

Role of Mg2+ in Insulin Secretion

The clinical evidence for a role of Mg2+ in insulin secretion is limited and less well studied than the effects of Mg2+ on insulin sensitivity, but several recent clinical studies suggest that T2DM patients with hypomagnesemia display reduced insulin secretion. In individuals without diabetes, decreased serum Mg2+ concentrations are associated with a diminished insulin secretion (15). Conversely, HOMA of β-cell activity was negatively correlated with the serum Mg2+ concentration in a Canadian cohort of patients with T2DM (50). However, this study focused mainly on the lipid metabolism and did not fully explore the effects on insulin secretion. Supplementation of individuals without diabetes with MgCl2 significantly increased β-cell function in a small randomized clinical trial (51). Here, we will examine the molecular mechanisms by which Mg2+ improves insulin secretion by showing how Mg2+ acts on the main actors involved in insulin secretion.

Glucokinase

After entering the pancreatic β-cells via GLUT2, glucose is converted to G6P by glucokinase. The action of glucokinase depends on MgATP2−. Recent studies show that the activity of glucokinase is regulated by MgATP2− at subphysiological concentrations (reported KM ∼0.15 mmol/L), suggesting that there is always sufficient MgATP2− available in the cell for glucokinase activity (52). However, there may exist a small cooperative effect of MgATP2− on glucose binding (52,53). Mg2+ deficiency may, therefore, reduce glucose binding to glucokinase by slowing down metabolism and indirectly reducing insulin secretion.

Glycolysis

G6P is further metabolized via glycolysis and the Krebs cycle, resulting in increased ATP levels. Although many enzymes in this metabolic process use MgATP as a cofactor (54), studies in erythrocytes have shown that glycolysis depends on intracellular Mg2+ with a half-maximal glycolysis flux at 0.03 mmol/L Mg2+. This is well below physiological intracellular Mg2+ values, even in Mg2+ deficient conditions (55).

KATP Channel

First described in 1984, KATP channels are the main regulators of the membrane potential in pancreatic β-cells (56). The KATP channel in β-cells consists of four Kir6.2 subunits and four regulatory sulfonylurea receptor (SUR)1 subunits, whose activity is controlled by the intracellular ATP-to-ADP ratio. In the presence of Mg2+, it is the balance between MgATP, physiologically ranging between 1 and 5 mmol/L, and MgADP levels that determines channel activity. Binding of both MgATP and MgADP to the nucleotide-binding sites of SUR1 subunits results in opening of the channel. By contrast, in the absence of Mg2+, ATP induces closure of the KATP channel by directly binding to Kir6.2 subunits (57). In high-glucose conditions, increased glycolysis shifts the balance toward ATP, concomitantly leading to reduced MgADP levels inducing channel closure and increased insulin secretion (58). This balance is the therapeutic target of sulfonylurea drugs, which induce channel closure by antagonizing the binding of Mg nucleotides on SUR1 (59). Thus, reduced intracellular Mg2+ concentrations, as a result of hypomagnesemia in T2DM, may reduce the MgATP and MgADP levels, favoring inhibition of the KATP channel and thereby indirectly stimulating insulin secretion. However, the exact effect of hypomagnesemia on intracellular MgATP levels remains to be examined.

L-Type Ca2+ Channel

Inhibition of KATP channels by increased ATP levels results in depolarization of the membrane, activating Ca2+ influx via the voltage-dependent L-type Ca2+ channel. In the pancreatic β-cell, the main L-type channels are of the Cav1.2 and Cav1.3 subtypes, of which Cav1.2 channels are the main contributors to insulin secretion (60,61). There is a wide range of literature showing that both intracellular and extracellular Mg2+ inhibits L-type Ca2+ channels (62–64). Although these findings suggest that hypomagnesemia would increase L-type channel activity in the short-term, in the long-term it has been indicated that hypomagnesemia reduces the expression of L-type Ca2+ channels and, thus, indirectly diminishes insulin secretion (65). However, it should be noted that these findings rely on measurements performed with cardiomyocytes and have not been confirmed in pancreatic β-cells.

Insulin Vesicle Release

Insulin vesicle release depends on Ca2+ binding that initiates exocytosis (45). Mg2+ fulfills an essential role in antagonizing Ca2+ and thus regulates insulin secretion by pancreatic β-cells. Atwater et al. (66) studied the importance of the Ca2+-to-Mg2+ ratio in glucose-induced insulin release in perfused rat pancreas and mouse islets. The results indicated that only a reduction of the physiological Mg2+ concentrations stimulated insulin secretion. Conversely, insulin secretion was inhibited only by diminished Ca2+ levels. Interestingly, a simultaneous reduction in Ca2+ and Mg2+, while maintaining their ratio constant, did not change the insulin release. Mg2+ deficiency inevitably changes the Ca2+-to-Mg2+ ratio and may therefore affect insulin secretion.

Novel Perspectives

Altogether, the regulation of KATP channels, L-type Ca2+ channels, and vesicle release points toward an inhibitory effect of Mg2+ on insulin secretion. These studies suggest that Mg2+ deficiency stimulates insulin release by the β-cells. However, a recent clinical study showed a positive correlation between Mg2+ concentration and first-phase insulin secretion (15). Why do hypomagnesemic T2DM patients suffer from reduced insulin secretion then? There may be multiple factors contributing to this paradox: 1) many of the studies of KATP channels and L-type Ca2+ channels are executed in cardiac cells and may therefore not be a good representation of the effects of Mg2+ in the pancreas; 2) most studies investigate short-term effects of Mg2+ on channel activity and may not represent long-term Mg2+ deficiency; 3) it has been shown that Mg2+ increases insulin synthesis at the transcriptional level (67); 4) all studies have focused on the effects of intracellular Mg2+, leaving the role of extracellular Mg2+ unknown; 5) Mg2+ is an important regulator of protein synthesis and cell proliferation (68) and may therefore regulate β-cell viability; and 6) Mg2+ deficiency may also regulate other factors, including serum K+ and Ca2+, and thereby indirectly affect insulin signaling. However, it should be emphasized that the role of Mg2+ in insulin secretion has only been examined by a small number of clinical studies. The current clinical evidence on the effect of Mg2+ on insulin secretion is too limited to draw firm conclusions on the physiological implications of Mg2+ in the pancreatic β-cell. Future clinical and experimental studies are necessary to resolve this question.

Mg2+ Homeostasis

Cellular Mg2+ Homeostasis

Since protein and DNA synthesis is highly dependent on intracellular Mg2+ availability, intracellular Mg2+ concentrations are tightly regulated (12). Intracellular Mg2+ concentrations are determined by the uptake via dedicated Mg2+ channels and transporters, including solute carrier family 41 member 1 (SLC41A1), magnesium transporter 1 (MagT1), and transient receptor potential melastatin type 6 and 7 (TRPM6 and TRPM7). The role of these Mg2+ transporters in the establishment of Mg2+ homeostasis has been reviewed in detail (12). Several groups have investigated the association between genetic variations in these Mg2+ transporters and risk for T2DM (69–71). Until now, a link between T2DM and TRPM7 or MagT1 has not been found. However, single nucleotide polymorphisms (SNPs) in TRPM6 or SLC41A1 have been associated with increased risk for T2DM (69,71). Interestingly, insulin may be an important regulator of cellular Mg2+ uptake. Studies in erythrocytes showed that insulin reduces serum Mg2+ levels and increases cytosolic Mg2+ concentrations (72). Indeed, insulin increases both glucose and Mg2+ uptake in pancreatic β-cells and cardiomyocytes, suggesting that glucose and Mg2+ homeostasis are linked (73,74). However, the molecular identity of the Mg2+ transporters involved in this mechanism has not been identified to date.

Body Mg2+ Homeostasis

Mg2+ homeostasis in the body is facilitated by the interplay of intestinal absorption, bone Mg2+ storage, and renal Mg2+ excretion (12). In the kidney, the bulk of filtered Mg2+ is reabsorbed passively in the proximal tubule (10–25%) and thick ascending limb of Henle loop (TAL) (60–80%). However, fine-tuning takes place in the distal convoluted tubule (DCT) (5–15%) where transcellular reabsorption determines the final urinary Mg2+ excretion, since no reabsorption takes place beyond the DCT (12).

In the DCT, Mg2+ is reabsorbed from the pro-urine by TRPM6 channels (12). Patients with TRPM6 mutations suffer from hypomagnesemia with secondary hypocalcemia (Mendelian Inheritance in Man: 602014) due to renal Mg2+ wasting (75,76). TRPM6 is highly regulated by dietary Mg2+ availability, epidermal growth factor, estrogen, pH, and ATP (77–81). Conversely, vitamin D and parathyroid hormone do not regulate Mg2+ reabsorption in the DCT (77). The transepithelial movement of Mg2+ is dependent on the electrochemical gradient that is set by Na+-K+-ATPase activity and depends on the local recycling of K+ transport via Kv1.1 at the apical membrane and Kir4.1 at the basolateral membrane (82–84). Although the basolateral Mg2+ extrusion mechanism in the DCT is still under debate, recent publications suggest that this might be facilitated by the SLC41A1 Na+-Mg2+ exchanger and is regulated by cyclin M2 (85–87).

Insulin Regulates Mg2+ Reabsorption in the Kidney

Hypomagnesemia in T2DM is primarily due to renal Mg2+ wasting (88). Insulin extracts from animal pancreas were introduced in medicine in the early 1920s saving the lives of many T2DM patients (89). The first article reporting increased blood Mg2+ and Na+ levels during treatment with impure insulin extracts was published in 1933 (90). However, it was not until the 1960s, when synthetic insulin was available and Mg2+ measurements were improved, that it became apparent that insulin regulates Mg2+ reabsorption in the kidney (91). Indeed, microperfusion experiments in mouse TAL segments show increased Mg2+ permeability after insulin stimulation (92). Moreover, in mouse DCT cells insulin stimulates Mg2+ uptake (93). Therefore, we will present an overview of the molecular targets of insulin in the regulation of renal Mg2+ transport.

TRPM6

TRPM6 was identified as the molecular target of insulin signaling in 2012 (94) (Fig. 3). Upon insulin binding to the receptor, an intracellular signaling cascade including phosphatidylinositol 3-kinase, Akt, and Rac1 is activated resulting in increased insertion of TRPM6 in the plasma membrane. Two SNPs in TRPM6 (p.Val1393Ile [rs3750425] and p.Lys1584Glu [rs2274924]) are associated with increased susceptibility for gestational diabetes mellitus (71). Patch clamp analysis showed that these mutations render the channel insensitive to insulin stimulation (94). Follow-up studies could not confirm associations between serum Mg2+ values and these two SNPs (69,95). However, these differences may be explained by the dietary Mg2+ intake of the subjects, since patients in the original study showed reduced Mg2+ intake (<250 mg/day) (71). The mRNA expression of TRPM6 is changed in diabetic rats, although results are contradictory and may depend on the experimental model used (96,97). Whereas some report increased TRPM6 expression (96), others show that TRPM6 is downregulated (97). Given that hypomagnesemia itself also stimulates TRPM6 expression (77,98), it is difficult to distinguish between the effect of hypomagnesemia and T2DM in these studies.

Figure 3
Figure 3

Insulin regulates electrolyte reabsorption in the distal convoluted tubule. Upon binding of insulin to its receptor, an intracellular signaling cascade including phosphatidylinositol 3-kinase (PI3K) and Akt increases the plasma membrane expression of the TRPM6 Mg2+ channel and the thiazide-sensitive NCC. Additionally, insulin may stimulate the activity of other channels, such as K+ channel Kir4.1 and the Na+-K+-ATPase. SPAK, STE20/SPS1-related, proline-alanine-rich kinase; WNK, with-no-lysine [K] kinases.

Na+-Cl− Cotransporter

In addition to its actions on TRPM6, insulin signaling in DCT increases Na+ reabsorption via the thiazide-sensitive Na+-Cl− cotransporter (NCC) (99–103). Insulin activates an intracellular signaling cascade that includes mTOR complex 2 (mTORC2) and stress-activated protein kinase/oxidative stress responsive kinase (SAPK/OSR1) to increase NCC phosphorylation and activity (99,101,102) (Fig. 3). It has been hypothesized that hyperinsulinemia in T2DM causes increased NCC activation and thus renal Na+ reabsorption, contributing to hypertension that is present in 75% of T2DM patients (104). This hypothesis is supported by studies in Zucker obese rats and db/db mice showing hyperinsulinemia, hypertension, and increased NCC activity (100,101).

Diabetes-DCT Paradox

Central in the theory of insulin-induced hypertension is that the hyperinsulinemic state causes overactivation of the insulin pathway resulting in increased NCC activity (99,101). In contrast, insulin resistance has been proposed to explain the reduced TRPM6 activity and hypomagnesemia in T2DM (94). Until now, it has been widely accepted that Na+ and Mg2+ transport in the DCT go hand in hand, since reduced NCC activity causes hypomagnesemia as shown in patients with Gitelman syndrome and in users of thiazide diuretics (105,106). However, in T2DM, Na+ and Mg2+ reabsorption in DCT may be uncoupled, resulting in increased Na+ reabsorption and decreased Mg2+ reabsorption. Elucidation of the molecular mechanisms of Na+ and Mg2+ cross talk and studies of the insulin resistance of DCT cells in T2DM may contribute to better understanding of the diabetes-DCT paradox.

Kir4.1 and Na+-K+-ATPase

Reports on diabetic retinopathy suggest that insulin regulates the potassium channel Kir4.1 in the retina (107,108). Given that Kir4.1 is also an important regulator of Na+ and Mg2+ transport in DCT, and patients with mutations in Kir4.1 develop hypomagnesemia and hypokalemia, future studies should include regulation of Kir4.1 in T2DM patients (109,110).

Additionally, insulin has been shown to increase Na+-K+-ATPase activity in several tissues including heart and muscle (111,112). Na+-K+-ATPase activity is decreased in animal models of T2DM (reviewed in 113,114). Within the DCT, the membrane expression of the Na+-K+-ATPase is regulated by TBC1 domain family, member 4 (TBC1D4), which is a substrate of Akt in the insulin pathway (115). Given that the expression of TBC1D4 in the DCT is regulated by dietary Mg2+ intake (98), the regulation of the Na+-K+-ATPase may be changed in hypomagnesemia via TBC1D4.

Other Factors Regulating Mg2+ Transport in T2DM

In the complex context of T2DM, many factors may play a role in the development of hypomagnesemia. In contrast to the well-described effects of insulin on renal electrolyte handling, other contributing factors are poorly studied. Therefore, rather than providing a definitive overview of impaired renal regulation of Mg2+ transport in T2DM, this part of the article aims to highlight contributors to hypomagnesemia that are underappreciated in current literature and should be subject for further examinations.

Glucose

Initial experiments in 1970s and 1980s showed that glucose increases urinary Mg2+ excretion (116,117). However, the molecular mechanism by which glucose regulates renal Mg2+ handling is unknown, and these early experiments do not take into account the action of insulin or diuresis. Recently, the Na+-GLUT2 sodium–glucose cotransporter 2 (sglt2) KO mouse, which is characterized by a marked glucosuria, was shown to have increased urinary Mg2+ excretion (118). These findings raise clinical concerns for the use of SGLT2 inhibitors. However, clinical trials with SGLT2 inhibitors have not provided any evidence that Mg2+ excretion is changed by SGLT2 inhibitor intake (119,120). Given the substantial glucosuria in T2DM, the physiological role of glucose in Mg2+ reabsorption can be questioned.

Hyperfiltration

Increased blood glucose values in T2DM result in hyperfiltration and increased renal urinary flow (121,122). Approximately 10–25% of the filtered Mg2+ is reabsorbed by the proximal tubules where water reabsorption precedes Mg2+ reabsorption, creating a favorable electrochemical gradient for Mg2+ reabsorption. Micropuncture studies have shown that a 1.9 ratio between the concentrations of Mg2+ in the tubular fluid and the interstitial fluid is necessary for passive Mg2+ reabsorption (123). Consequently, increased urinary volume in T2DM patients will dilute the Mg2+ concentration in the pro-urine reducing the transepithelial chemical Mg2+ gradient in the proximal tubule. Mg2+ reabsorption in TAL and DCT is inversely correlated to urinary flow. Given that increased glomerular filtration results in high urinary flow rates, hyperfiltration may reduce Mg2+ reabsorption in T2DM patients.

Oxidative Stress

One of the main contributors to diabetic nephropathy is the oxidative stress in the kidney (124). Interestingly, oxidative stress has been shown to reduce TRPM6 activity (125), and as a result, Mg2+ uptake may be diminished in people with diabetes. Previously, methionine sulfoxide reductase B1 (MSRB1) was shown to prevent the effects of oxidative stress on TRPM6 by reducing oxidation of the channel. However, studies of rats with STZ-induced diabetes showed reduced Msrb1 expression (126). Thus, oxidative stress may contribute to hypomagnesemia in T2DM.

Conclusions and Perspectives

Over the past two decades, there has been a staggering amount of clinical evidence showing a tight association between hypomagnesemia and T2DM. A recent cross-sectional study has shown that hypomagnesemia is associated with an increased risk for complications, including retinopathy, nephropathy, and foot ulcers (127). Importantly, Mg2+ supplementation improved insulin sensitivity and metabolic control in a double-blind randomized trial, suggesting that Mg2+ is an important factor in the etiology and management of T2DM (9,10). So far, the clinical trials that have been performed using Mg2+ supplementation to improve T2DM have mainly focused on general parameters such as blood glucose or HbA1c levels. Therefore, well-designed, double-blind randomized trials in T2DM patients with hypomagnesemia studying the long-term effects of Mg2+ supplementation on T2DM pathophysiology and disease progression are now warranted.

The prevalence of hypomagnesemia in T2DM has been reported to range between 14 and 48%, meaning that millions of people worldwide are affected (4). Nevertheless, serum Mg2+ levels are not routinely determined in T2DM patients. Provided that hypomagnesemia is associated with conditions that are often present in T2DM, including hypertension, hypokalemia, and muscle cramps, more clinical attention is necessary to address this problem (12). Patients using widely prescribed drugs such as thiazide diuretics, proton pump inhibitors, and calcineurin inhibitors are especially at risk for developing hypomagnesemia and should be closely monitored (128,129). Additionally, patients with diabetic neuropathy who have episodes of diarrhea may suffer from intestinal malabsorption of Mg2+, which is another risk factor for hypomagnesemia.

Despite the widespread clinical evidence of the association of hypomagnesemia and T2DM, the molecular mechanisms of Mg2+ on insulin secretion and insulin resistance are still far from understood. Currently, the strongest line of evidence supports an effect of Mg2+ on insulin sensitivity (24–27). Small-scale fundamental studies have shown that Mg2+ is essential for insulin receptor phosphorylation, but the effect of Mg2+ on downstream targets in the muscle, liver, and adipocytes is largely unknown. The role of Mg2+ in the regulation of insulin secretion is more controversial and hampered by the limited number of clinical and experimental studies. In contrast, there have been significant advances demonstrating the important role of insulin in the regulation of Mg2+ reabsorption via TRPM6 in the kidney. Insulin resistance reduces renal Mg2+ reabsorption resulting in urinary Mg2+ wasting. As a consequence, people with diabetes may end up in a vicious circle in which hypomagnesemia enhances insulin resistance and insulin resistance causes hypomagnesemia. However, the picture is still far from complete, and more studies are required to fully understand the complex and dynamic role of Mg2+ in T2DM.

Article Information

Acknowledgments. The authors state their gratitude to Steef Kurstjens (Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands) for the careful reading of the manuscript.

Funding. This work was supported by grants from the Netherlands Organisation for Scientific Research (VICI 016.130.668) and the EURenOmics project from the European Union Seventh Framework Programme (FP7/2007–2013) (agreement no. 305608). J.H.F.d.B. is supported by grants from the Netherlands Organisation for Scientific Research (Rubicon 825.14.021) and the Dutch Kidney Foundation (Nierstichting) (Kolff 14OKG17).

Duality of Interest. No potential conflicts of interest relevant to this article were reported.

  • Received July 24, 2015.
  • Accepted September 10, 2015.

References

  1. ↵
    1. Olokoba AB,
    2. Obateru OA,
    3. Olokoba LB
    . Type 2 diabetes mellitus: a review of current trends. Oman Med J 2012;27:269–273pmid:23071876
    OpenUrlCrossRefPubMed
  2. ↵
    1. Bergman M
    . Pathophysiology of prediabetes and treatment implications for the prevention of type 2 diabetes mellitus. Endocrine 2013;43:504–513pmid:23132321
    OpenUrlCrossRefPubMedWeb of Science
  3. ↵
    1. Martin HE,
    2. Wertman M
    . Serum potassium, magnesium, and calcium levels in diabetic acidosis. J Clin Invest 1947;26:217–228pmid:16695408
    OpenUrlCrossRefPubMedWeb of Science
  4. ↵
    1. Pham PC,
    2. Pham PM,
    3. Pham SV,
    4. Miller JM,
    5. Pham PT
    . Hypomagnesemia in patients with type 2 diabetes. Clin J Am Soc Nephrol 2007;2:366–373pmid:17699436
    OpenUrlAbstract/FREE Full Text
  5. ↵
    1. Chaudhary DP,
    2. Sharma R,
    3. Bansal DD
    . Implications of magnesium deficiency in type 2 diabetes: a review. Biol Trace Elem Res 2010;134:119–129pmid:19629403
    OpenUrlCrossRefPubMedWeb of Science
  6. ↵
    1. Pham PC,
    2. Pham PM,
    3. Pham PA, et al
    . Lower serum magnesium levels are associated with more rapid decline of renal function in patients with diabetes mellitus type 2. Clin Nephrol 2005;63:429–436pmid:15960144
    OpenUrlCrossRefPubMed
  7. ↵
    1. Dong JY,
    2. Xun P,
    3. He K,
    4. Qin LQ
    . Magnesium intake and risk of type 2 diabetes: meta-analysis of prospective cohort studies. Diabetes Care 2011;34:2116–2122pmid:21868780
    OpenUrlAbstract/FREE Full Text
  8. ↵
    1. Guerrero-Romero F,
    2. Rodríguez-Morán M
    . Oral magnesium supplementation: an adjuvant alternative to facing the worldwide challenge of type 2 diabetes? Cir Cir 2014;82:282–289 [in Spanish]pmid:25238470
    OpenUrlPubMed
  9. ↵
    1. Guerrero-Romero F,
    2. Simental-Mendía LE,
    3. Hernández-Ronquillo G,
    4. Rodriguez-Morán M
    . Oral magnesium supplementation improves glycaemic status in subjects with prediabetes and hypomagnesaemia: a double-blind placebo-controlled randomized trial. Diabetes Metab 2015;41:202–207pmid:25937055
    OpenUrlCrossRefPubMed
  10. ↵
    1. Rodríguez-Morán M,
    2. Guerrero-Romero F
    . Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: a randomized double-blind controlled trial. Diabetes Care 2003;26:1147–1152pmid:12663588
    OpenUrlAbstract/FREE Full Text
  11. ↵
    Rodríguez-Morán M, Simental Mendia LE, Zambrano Galvan G, Guerrero-Romero F. The role of magnesium in type 2 diabetes: a brief based-clinical review. Magnes Res 2011;24:156–162
  12. ↵
    1. de Baaij JHF,
    2. Hoenderop JGJ,
    3. Bindels RJM
    . Magnesium in man: implications for health and disease. Physiol Rev 2015;95:1–46pmid:25540137
    OpenUrlAbstract/FREE Full Text
  13. ↵
    1. Barbagallo M,
    2. Dominguez LJ
    . Magnesium metabolism in type 2 diabetes mellitus, metabolic syndrome and insulin resistance. Arch Biochem Biophys 2007;458:40–47pmid:16808892
    OpenUrlCrossRefPubMedWeb of Science
  14. Fröjdö S, Vidal H, Pirola L. Alterations of insulin signaling in type 2 diabetes: a review of the current evidence from humans. Biochim Biophys Acta 2009;1792:83–92
  15. ↵
    1. Rodríguez-Morán M,
    2. Guerrero-Romero F
    . Insulin secretion is decreased in non-diabetic individuals with hypomagnesaemia. Diabetes Metab Res Rev 2011;27:590–596pmid:21488144
    OpenUrlCrossRefPubMed
  16. ↵
    1. Günther T
    . The biochemical function of Mg²+ in insulin secretion, insulin signal transduction and insulin resistance. Magnes Res 2010;23:5–18pmid:20228013
    OpenUrlPubMed
    1. Takaya J,
    2. Higashino H,
    3. Kobayashi Y
    . Intracellular magnesium and insulin resistance. Magnes Res 2004;17:126–136pmid:15319146
    OpenUrlPubMed
  18. ↵
    1. Barbagallo M,
    2. Dominguez LJ,
    3. Galioto A, et al
    . Role of magnesium in insulin action, diabetes and cardio-metabolic syndrome X. Mol Aspects Med 2003;24:39–52pmid:12537988
    OpenUrlCrossRefPubMed
  19. ↵
    1. Guyton AC, ,
    2. Hall JE
    . Textbook of Medical Physiology. 11th ed. Philadelphia, Saunders, 2006
  20. ↵
    1. Humphries S,
    2. Kushner H,
    3. Falkner B
    . Low dietary magnesium is associated with insulin resistance in a sample of young, nondiabetic Black Americans. Am J Hypertens 1999;12:747–756pmid:10480466
    OpenUrlAbstract/FREE Full Text
  21. ↵
    1. Lima MdeL,
    2. Cruz T,
    3. Rodrigues LE, et al
    . Serum and intracellular magnesium deficiency in patients with metabolic syndrome--evidences for its relation to insulin resistance. Diabetes Res Clin Pract 2009;83:257–262pmid:19124169
    OpenUrlCrossRefPubMed
  22. ↵
    1. Nadler JL,
    2. Buchanan T,
    3. Natarajan R,
    4. Antonipillai I,
    5. Bergman R,
    6. Rude R
    . Magnesium deficiency produces insulin resistance and increased thromboxane synthesis. Hypertension 1993;21:1024–1029pmid:8505087
    OpenUrlCrossRefPubMed
  23. ↵
    1. Hubbard SR
    . Crystal structure of the activated insulin receptor tyrosine kinase in complex with peptide substrate and ATP analog. EMBO J 1997;16:5572–5581pmid:9312016
    OpenUrlAbstract/FREE Full Text
  24. ↵
    1. Vicario PP,
    2. Bennun A
    . Separate effects of Mg2+, MgATP, and ATP4- on the kinetic mechanism for insulin receptor tyrosine kinase. Arch Biochem Biophys 1990;278:99–105pmid:2157363
    OpenUrlCrossRefPubMed
  25. ↵
    1. Viñals F,
    2. Camps M,
    3. Testar X,
    4. Palacín M,
    5. Zorzano A
    . Effect of cations on the tyrosine kinase activity of the insulin receptor: inhibition by fluoride is magnesium dependent. Mol Cell Biochem 1997;171:69–73pmid:9201698
    OpenUrlCrossRefPubMed
  26. ↵
    1. Paxton R,
    2. Ye L
    . Regulation of heart insulin receptor tyrosine kinase activity by magnesium and spermine. Mol Cell Biochem 2005;277:7–17pmid:16132709
    OpenUrlCrossRefPubMed
  27. ↵
    1. Suárez A,
    2. Pulido N,
    3. Casla A,
    4. Casanova B,
    5. Arrieta FJ,
    6. Rovira A
    . Impaired tyrosine-kinase activity of muscle insulin receptors from hypomagnesaemic rats. Diabetologia 1995;38:1262–1270pmid:8582534
    OpenUrlCrossRefPubMedWeb of Science
  28. ↵
    1. Reis MA,
    2. Reyes FG,
    3. Saad MJ,
    4. Velloso LA
    . Magnesium deficiency modulates the insulin signaling pathway in liver but not muscle of rats. J Nutr 2000;130:133–138pmid:10720159
    OpenUrlAbstract/FREE Full Text
  29. ↵
    1. Biddinger SB,
    2. Kahn CR
    . From mice to men: insights into the insulin resistance syndromes. Annu Rev Physiol 2006;68:123–158pmid:16460269
    OpenUrlCrossRefPubMedWeb of Science
  30. ↵
    1. Solaimani H,
    2. Soltani N,
    3. MaleKzadeh K, et al
    . Modulation of GLUT4 expression by oral administration of Mg(2+) to control sugar levels in STZ-induced diabetic rats. Can J Physiol Pharmacol 2014;92:438–444pmid:24821133
    OpenUrlCrossRefPubMed
  31. ↵
    1. Ha BG,
    2. Park JE,
    3. Cho HJ,
    4. Shon YH
    . Stimulatory effects of balanced deep sea water on mitochondrial biogenesis and function. PLoS One 2015;10:e0129972pmid:26068191
    OpenUrlCrossRefPubMed
  32. ↵
    1. McNeill DA,
    2. Herbein JH,
    3. Ritchey SJ
    . Hepatic gluconeogenic enzymes, plasma insulin and glucagon response to magnesium deficiency and fasting. J Nutr 1982;112:736–743pmid:6279807
    OpenUrlAbstract/FREE Full Text
  33. ↵
    Takaya J, Iharada A, Okihana H, Kaneko K. Down-regulation of hepatic phosphoenolpyruvate carboxykinase expression in magnesium-deficient rats. Magnes Res 2012;25:131–139
  34. ↵
    1. Uysal KT,
    2. Wiesbrock SM,
    3. Marino MW,
    4. Hotamisligil GS
    . Protection from obesity-induced insulin resistance in mice lacking TNF-alpha function. Nature 1997;389:610–614pmid:9335502
    OpenUrlCrossRefPubMedWeb of Science
  35. ↵
    1. de Luca C,
    2. Olefsky JM
    . Inflammation and insulin resistance. FEBS Lett 2008;582:97–105pmid:18053812
    OpenUrlCrossRefPubMedWeb of Science
  36. ↵
    1. Weglicki WB,
    2. Phillips TM,
    3. Freedman AM,
    4. Cassidy MM,
    5. Dickens BF
    . Magnesium-deficiency elevates circulating levels of inflammatory cytokines and endothelin. Mol Cell Biochem 1992;110:169–173pmid:1584207
    OpenUrlCrossRefPubMedWeb of Science
  37. ↵
    Rodriguez-Moran M, Guerrero-Romero F. Elevated concentrations of TNF-alpha are related to low serum magnesium levels in obese subjects. Magnes Res 2004;17:189–196
  38. ↵
    1. Bussière FI,
    2. Gueux E,
    3. Rock E, et al
    . Increased phagocytosis and production of reactive oxygen species by neutrophils during magnesium deficiency in rats and inhibition by high magnesium concentration. Br J Nutr 2002;87:107–113pmid:11895162
    OpenUrlCrossRefPubMed
  39. ↵
    1. Rodríguez-Morán M,
    2. Guerrero-Romero F
    . Serum magnesium and C-reactive protein levels. Arch Dis Child 2008;93:676–680pmid:17641003
    OpenUrlAbstract/FREE Full Text
  40. ↵
    1. Simental-Mendía LE,
    2. Rodríguez-Morán M,
    3. Guerrero-Romero F
    . Oral magnesium supplementation decreases C-reactive protein levels in subjects with prediabetes and hypomagnesemia: a clinical randomized double-blind placebo-controlled trial. Arch Med Res 2014;45:325–330pmid:24814039
    OpenUrlCrossRefPubMed
  41. ↵
    1. Henriksen EJ,
    2. Diamond-Stanic MK,
    3. Marchionne EM
    . Oxidative stress and the etiology of insulin resistance and type 2 diabetes. Free Radic Biol Med 2011;51:993–999pmid:21163347
    OpenUrlCrossRefPubMed
  42. ↵
    1. Li Q,
    2. Zhu X,
    3. Ishikura S, et al
    . Ca²⁺ signals promote GLUT4 exocytosis and reduce its endocytosis in muscle cells. Am J Physiol Endocrinol Metab 2014;307:E209–E224pmid:24895284
    OpenUrlAbstract/FREE Full Text
  43. ↵
    1. Takaya J,
    2. Yamato F,
    3. Higashino H,
    4. Kaneko K
    . Intracellular magnesium and adipokines in umbilical cord plasma and infant birth size. Pediatr Res 2007;62:700–703pmid:17957162
    OpenUrlCrossRefPubMedWeb of Science
  44. ↵
    1. Matschinsky FM
    . Regulation of pancreatic beta-cell glucokinase: from basics to therapeutics. Diabetes 2002;51(Suppl. 3):S394–S404pmid:12475782
    OpenUrlAbstract/FREE Full Text
  45. ↵
    1. Ashcroft FM,
    2. Rorsman P
    . K(ATP) channels and islet hormone secretion: new insights and controversies. Nat Rev Endocrinol 2013;9:660–669pmid:24042324
    OpenUrlCrossRefPubMed
  46. ↵
    1. Braun M,
    2. Ramracheya R,
    3. Bengtsson M, et al
    . Voltage-gated ion channels in human pancreatic beta-cells: electrophysiological characterization and role in insulin secretion. Diabetes 2008;57:1618–1628pmid:18390794
    OpenUrlAbstract/FREE Full Text
  47. ↵
    1. Weir GC,
    2. Bonner-Weir S
    . Five stages of evolving beta-cell dysfunction during progression to diabetes. Diabetes 2004;53(Suppl. 3):S16–S21pmid:15561905
    OpenUrlAbstract/FREE Full Text
  48. ↵
    1. Meier JJ,
    2. Bonadonna RC
    . Role of reduced β-cell mass versus impaired β-cell function in the pathogenesis of type 2 diabetes. Diabetes Care 2013;36(Suppl. 2):S113–S119pmid:23882035
    OpenUrlFREE Full Text
  49. ↵
    1. Billings LK,
    2. Florez JC
    . The genetics of type 2 diabetes: what have we learned from GWAS? Ann N Y Acad Sci 2010;1212:59–77pmid:21091714
    OpenUrlCrossRefPubMedWeb of Science
  50. ↵
    1. Randell EW,
    2. Mathews M,
    3. Gadag V,
    4. Zhang H,
    5. Sun G
    . Relationship between serum magnesium values, lipids and anthropometric risk factors. Atherosclerosis 2008;196:413–419pmid:17161404
    OpenUrlCrossRefPubMedWeb of Science
  51. ↵
    1. Guerrero-Romero F,
    2. Rodríguez-Morán M
    . Magnesium improves the beta-cell function to compensate variation of insulin sensitivity: double-blind, randomized clinical trial. Eur J Clin Invest 2011;41:405–410pmid:21241290
    OpenUrlCrossRefPubMed
  52. ↵
    1. Molnes J,
    2. Teigen K,
    3. Aukrust I, et al
    . Binding of ATP at the active site of human pancreatic glucokinase--nucleotide-induced conformational changes with possible implications for its kinetic cooperativity. FEBS J 2011;278:2372–2386pmid:21569204
    OpenUrlCrossRefPubMed
  53. ↵
    1. Storer AC,
    2. Cornish-Bowden A
    . Kinetics of rat liver glucokinase. Co-operative interactions with glucose at physiologically significant concentrations. Biochem J 1976;159:7–14pmid:999645
    OpenUrlAbstract/FREE Full Text
  54. ↵
    1. Garfinkel L,
    2. Garfinkel D
    . Magnesium regulation of the glycolytic pathway and the enzymes involved. Magnesium 1985;4:60–72pmid:2931560
    OpenUrlPubMed
  55. ↵
    1. Laughlin MR,
    2. Thompson D
    . The regulatory role for magnesium in glycolytic flux of the human erythrocyte. J Biol Chem 1996;271:28977–28983pmid:8910548
    OpenUrlAbstract/FREE Full Text
  56. ↵
    1. Ashcroft FM,
    2. Harrison DE,
    3. Ashcroft SJ
    . Glucose induces closure of single potassium channels in isolated rat pancreatic beta-cells. Nature 1984;312:446–448pmid:6095103
    OpenUrlCrossRefPubMedWeb of Science
  57. ↵
    1. Ashcroft FM
    . ATP-sensitive potassium channelopathies: focus on insulin secretion. J Clin Invest 2005;115:2047–2058pmid:16075046
    OpenUrlCrossRefPubMedWeb of Science
  58. ↵
    1. Proks P,
    2. de Wet H,
    3. Ashcroft FM
    . Sulfonylureas suppress the stimulatory action of Mg-nucleotides on Kir6.2/SUR1 but not Kir6.2/SUR2A KATP channels: a mechanistic study. J Gen Physiol 2014;144:469–486pmid:25348414
    OpenUrlAbstract/FREE Full Text
  59. ↵
    1. Ashcroft FM
    . New uses for old drugs: neonatal diabetes and sulphonylureas. Cell Metab 2010;11:179–181pmid:20197050
    OpenUrlCrossRefPubMed
  60. ↵
    1. Schulla V,
    2. Renström E,
    3. Feil R, et al
    . Impaired insulin secretion and glucose tolerance in beta cell-selective Ca(v)1.2 Ca2+ channel null mice. EMBO J 2003;22:3844–3854pmid:12881419
    OpenUrlAbstract/FREE Full Text
  61. ↵
    1. Nitert MD,
    2. Nagorny CL,
    3. Wendt A,
    4. Eliasson L,
    5. Mulder H
    . CaV1.2 rather than CaV1.3 is coupled to glucose-stimulated insulin secretion in INS-1 832/13 cells. J Mol Endocrinol 2008;41:1–11pmid:18562674
    OpenUrlAbstract/FREE Full Text
  62. ↵
    1. Wang M,
    2. Berlin JR
    . Channel phosphorylation and modulation of L-type Ca2+ currents by cytosolic Mg2+ concentration. Am J Physiol Cell Physiol 2006;291:C83–C92pmid:16481369
    OpenUrlAbstract/FREE Full Text
    1. Wang M,
    2. Tashiro M,
    3. Berlin JR
    . Regulation of L-type calcium current by intracellular magnesium in rat cardiac myocytes. J Physiol 2004;555:383–396pmid:14617671
    OpenUrlCrossRefPubMedWeb of Science
  64. ↵
    1. Zhang J,
    2. Berra-Romani R,
    3. Sinnegger-Brauns MJ,
    4. Striessnig J,
    5. Blaustein MP,
    6. Matteson DR
    . Role of Cav1.2 L-type Ca2+ channels in vascular tone: effects of nifedipine and Mg2+. Am J Physiol Heart Circ Physiol 2007;292:H415–H425pmid:16980345
    OpenUrlAbstract/FREE Full Text
  65. ↵
    Shimaoka T, Wang Y, Morishima M, Miyamoto S, Ono K. Hypomagnesemic down-regulation of L-type Ca(2+) channel in cardiomyocyte as an arrhythmogenic substrate in rats. Pathophysiology 2015;22:87–93
  66. ↵
    1. Atwater I,
    2. Frankel BJ,
    3. Rojas E,
    4. Grodsky GM
    . Beta cell membrane potential and insulin release; role of calcium and calcium:magnesium ratio. Q J Exp Physiol 1983;68:233–245pmid:6344119
    OpenUrlCrossRefPubMed
  67. ↵
    1. Balon TW,
    2. Gu JL,
    3. Tokuyama Y,
    4. Jasman AP,
    5. Nadler JL
    . Magnesium supplementation reduces development of diabetes in a rat model of spontaneous NIDDM. Am J Physiol 1995;269:E745–E752pmid:7485490
    OpenUrlPubMed
  68. ↵
    Rubin H. The membrane, magnesium, mitosis (MMM) model of cell proliferation control. Magnes Res 2005;18:268–274
  69. ↵
    1. Chan KH,
    2. Chacko SA,
    3. Song Y, et al
    . Genetic variations in magnesium-related ion channels may affect diabetes risk among African American and Hispanic American women. J Nutr 2015;145:418–424pmid:25733456
    OpenUrlAbstract/FREE Full Text
    1. Romero JR,
    2. Castonguay AJ,
    3. Barton NS,
    4. Germer S,
    5. Martin M,
    6. Zee RY
    . Gene variation of the transient receptor potential cation channel, subfamily M, members 6 (TRPM6) and 7 (TRPM7), and type 2 diabetes mellitus: a case-control study. Transl Res 2010;156:235–241pmid:20875900
    OpenUrlCrossRefPubMed
  71. ↵
    1. Song Y,
    2. Hsu YH,
    3. Niu T,
    4. Manson JE,
    5. Buring JE,
    6. Liu S
    . Common genetic variants of the ion channel transient receptor potential membrane melastatin 6 and 7 (TRPM6 and TRPM7), magnesium intake, and risk of type 2 diabetes in women. BMC Med Genet 2009;10:4pmid:19149903
    OpenUrlCrossRefPubMed
  72. ↵
    1. Paolisso G,
    2. Sgambato S,
    3. Passariello N, et al
    . Insulin induces opposite changes in plasma and erythrocyte magnesium concentrations in normal man. Diabetologia 1986;29:644–647pmid:3539681
    OpenUrlCrossRefPubMedWeb of Science
  73. ↵
    1. Gylfe E
    . Insulin secretagogues induce Ca(2+)-like changes in cytoplasmic Mg2+ in pancreatic beta-cells. Biochim Biophys Acta 1990;1055:82–86pmid:2223873
    OpenUrlPubMed
  74. ↵
    1. Romani AM,
    2. Matthews VD,
    3. Scarpa A
    . Parallel stimulation of glucose and Mg(2+) accumulation by insulin in rat hearts and cardiac ventricular myocytes. Circ Res 2000;86:326–333pmid:10679485
    OpenUrlAbstract/FREE Full Text
  75. ↵
    1. Schlingmann KP,
    2. Weber S,
    3. Peters M, et al
    . Hypomagnesemia with secondary hypocalcemia is caused by mutations in TRPM6, a new member of the TRPM gene family. Nat Genet 2002;31:166–170pmid:12032568
    OpenUrlCrossRefPubMedWeb of Science
  76. ↵
    1. Walder RY,
    2. Landau D,
    3. Meyer P, et al
    . Mutation of TRPM6 causes familial hypomagnesemia with secondary hypocalcemia. Nat Genet 2002;31:171–174pmid:12032570
    OpenUrlCrossRefPubMedWeb of Science
  77. ↵
    1. Groenestege WM,
    2. Hoenderop JG,
    3. van den Heuvel L,
    4. Knoers N,
    5. Bindels RJ
    . The epithelial Mg2+ channel transient receptor potential melastatin 6 is regulated by dietary Mg2+ content and estrogens. J Am Soc Nephrol 2006;17:1035–1043pmid:16524949
    OpenUrlAbstract/FREE Full Text
    1. Li M,
    2. Du J,
    3. Jiang J, et al
    . Molecular determinants of Mg2+ and Ca2+ permeability and pH sensitivity in TRPM6 and TRPM7. J Biol Chem 2007;282:25817–25830pmid:17599911
    OpenUrlAbstract/FREE Full Text
    1. Cao G,
    2. van der Wijst J,
    3. van der Kemp A,
    4. van Zeeland F,
    5. Bindels RJ,
    6. Hoenderop JG
    . Regulation of the epithelial Mg2+ channel TRPM6 by estrogen and the associated repressor protein of estrogen receptor activity (REA). J Biol Chem 2009;284:14788–14795pmid:19329436
    OpenUrlAbstract/FREE Full Text
    1. Thebault S,
    2. Alexander RT,
    3. Tiel Groenestege WM,
    4. Hoenderop JG,
    5. Bindels RJ
    . EGF increases TRPM6 activity and surface expression. J Am Soc Nephrol 2009;20:78–85pmid:19073827
    OpenUrlAbstract/FREE Full Text
  81. ↵
    1. de Baaij JH,
    2. Blanchard MG,
    3. Lavrijsen M,
    4. Leipziger J,
    5. Bindels RJ,
    6. Hoenderop JG
    . P2X4 receptor regulation of transient receptor potential melastatin type 6 (TRPM6) Mg2+ channels. Pflugers Arch 2014;466:1941–1952pmid:24413910
    OpenUrlCrossRefPubMed
  82. ↵
    1. de Baaij JH,
    2. Dorresteijn EM,
    3. Hennekam EA, et al
    . Recurrent FXYD2 p.Gly41Arg mutation in patients with isolated dominant hypomagnesaemia. Nephrol Dial Transplant 2015;30:952–957pmid:25765846
    OpenUrlAbstract/FREE Full Text
    1. Glaudemans B,
    2. van der Wijst J,
    3. Scola RH, et al
    . A missense mutation in the Kv1.1 voltage-gated potassium channel-encoding gene KCNA1 is linked to human autosomal dominant hypomagnesemia. J Clin Invest 2009;119:936–942pmid:19307729
    OpenUrlCrossRefPubMedWeb of Science
  84. ↵
    1. Reichold M,
    2. Zdebik AA,
    3. Lieberer E, et al
    . KCNJ10 gene mutations causing EAST syndrome (epilepsy, ataxia, sensorineural deafness, and tubulopathy) disrupt channel function. Proc Natl Acad Sci U S A 2010;107:14490–14495pmid:20651251
    OpenUrlAbstract/FREE Full Text
  85. ↵
    1. Arjona FJ,
    2. de Baaij JH,
    3. Schlingmann KP, et al
    . CNNM2 mutations cause impaired brain development and seizures in patients with hypomagnesemia. PLoS Genet 2014;10:e1004267pmid:24699222
    OpenUrlCrossRefPubMed
    1. Hurd TW,
    2. Otto EA,
    3. Mishima E, et al
    . Mutation of the Mg2+ transporter SLC41A1 results in a nephronophthisis-like phenotype. J Am Soc Nephrol 2013;24:967–977pmid:23661805
    OpenUrlAbstract/FREE Full Text
  87. ↵
    1. Kolisek M,
    2. Nestler A,
    3. Vormann J,
    4. Schweigel-Röntgen M
    . Human gene SLC41A1 encodes for the Na+/Mg²+ exchanger. Am J Physiol Cell Physiol 2012;302:C318–C326pmid:22031603
    OpenUrlAbstract/FREE Full Text
  88. ↵
    1. McNair P,
    2. Christensen MS,
    3. Christiansen C,
    4. Madsbad S,
    5. Transbøl I
    . Renal hypomagnesaemia in human diabetes mellitus: its relation to glucose homeostasis. Eur J Clin Invest 1982;12:81–85pmid:6802656
    OpenUrlCrossRefPubMedWeb of Science
  89. ↵
    1. Banting FG,
    2. Best CH,
    3. Collip JB,
    4. Campbell WR,
    5. Fletcher AA
    . Pancreatic extracts in the treatment of diabetes mellitus. Can Med Assoc J 1922;12:141–146pmid:20314060
    OpenUrlPubMed
  90. ↵
    1. Atchley DW,
    2. Loeb RF,
    3. Richards DW,
    4. Benedict EM,
    5. Driscoll ME
    . On diabetic acidosis: a detailed study of electrolyte balances following the withdrawal and reestablishment of insulin therapy. J Clin Invest 1933;12:297–326pmid:16694129
    OpenUrlCrossRefPubMed
  91. ↵
    1. Aikaws JK
    . Effect of glucose and insulin on magnesium metabolism in rabbits. A study with Mg28. Proc Soc Exp Biol Med 1960;103:363–366pmid:13792168
    OpenUrlAbstract/FREE Full Text
  92. ↵
    1. Mandon B,
    2. Siga E,
    3. Chabardes D,
    4. Firsov D,
    5. Roinel N,
    6. De Rouffignac C
    . Insulin stimulates Na+, Cl-, Ca2+, and Mg2+ transports in TAL of mouse nephron: cross-potentiation with AVP. Am J Physiol 1993;265:F361–F369pmid:8214094
    OpenUrlPubMedWeb of Science
  93. ↵
    1. Dai LJ,
    2. Ritchie G,
    3. Bapty BW,
    4. Kerstan D,
    5. Quamme GA
    . Insulin stimulates Mg2+ uptake in mouse distal convoluted tubule cells. Am J Physiol 1999;277:F907–F913pmid:10600938
    OpenUrlPubMed
  94. ↵
    1. Nair AV,
    2. Hocher B,
    3. Verkaart S, et al
    . Loss of insulin-induced activation of TRPM6 magnesium channels results in impaired glucose tolerance during pregnancy. Proc Natl Acad Sci U S A 2012;109:11324–11329pmid:22733750
    OpenUrlAbstract/FREE Full Text
  95. ↵
    1. Hruby A,
    2. Ngwa JS,
    3. Renström F, et al
    . Higher magnesium intake is associated with lower fasting glucose and insulin, with no evidence of interaction with select genetic loci, in a meta-analysis of 15 CHARGE Consortium Studies. J Nutr 2013;143:345–353pmid:23343670
    OpenUrlAbstract/FREE Full Text
  96. ↵
    1. Lee CT,
    2. Lien YH,
    3. Lai LW,
    4. Chen JB,
    5. Lin CR,
    6. Chen HC
    . Increased renal calcium and magnesium transporter abundance in streptozotocin-induced diabetes mellitus. Kidney Int 2006;69:1786–1791pmid:16557223
    OpenUrlCrossRefPubMedWeb of Science
  97. ↵
    Takayanagi K, Shimizu T, Tayama Y, et al. Down-regulation of transient receptor potential (TRP) M6 channel as a cause of hypermagnesiuric hypomagnesemia in obese type-2 diabetic rats. Am J Physiol Renal Physiol 2015;308:F1386–F1397
  98. ↵
    1. de Baaij JH,
    2. Groot Koerkamp MJ,
    3. Lavrijsen M, et al
    . Elucidation of the distal convoluted tubule transcriptome identifies new candidate genes involved in renal Mg(2+) handling. Am J Physiol Renal Physiol 2013;305:F1563–F1573pmid:24089412
    OpenUrlAbstract/FREE Full Text
  99. ↵
    1. Chávez-Canales M,
    2. Arroyo JP,
    3. Ko B, et al
    . Insulin increases the functional activity of the renal NaCl cotransporter. J Hypertens 2013;31:303–311pmid:23303355
    OpenUrlPubMedWeb of Science
  100. ↵
    Komers R, Rogers S, Oyama TT, et al. Enhanced phosphorylation of Na(+)-Cl- co-transporter in experimental metabolic syndrome: role of insulin. Clin Sci (Lond) 2012;123:635–647
  101. ↵
    1. Nishida H,
    2. Sohara E,
    3. Nomura N, et al
    . Phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in hyperinsulinemic db/db mice. Hypertension 2012;60:981–990pmid:22949526
    OpenUrlAbstract/FREE Full Text
  102. ↵
    1. Sohara E,
    2. Rai T,
    3. Yang SS, et al
    . Acute insulin stimulation induces phosphorylation of the Na-Cl cotransporter in cultured distal mpkDCT cells and mouse kidney. PLoS One 2011;6:e24277pmid:21909387
    OpenUrlCrossRefPubMed
  103. ↵
    1. Takahashi D,
    2. Mori T,
    3. Nomura N, et al
    . WNK4 is the major WNK positively regulating NCC in the mouse kidney. Biosci Rep 2014;34:34pmid:24655003
    OpenUrlCrossRefPubMed
  104. ↵
    1. Schutta MH
    . Diabetes and hypertension: epidemiology of the relationship and pathophysiology of factors associated with these comorbid conditions. J Cardiometab Syndr 2007;2:124–130pmid:17684469
    OpenUrlCrossRefPubMed
  105. ↵
    1. Knoers NV,
    2. Levtchenko EN
    . Gitelman syndrome. Orphanet J Rare Dis 2008;3:22pmid:18667063
    OpenUrlCrossRefPubMed
  106. ↵
    1. Davies DL,
    2. Fraser R
    . Do diuretics cause magnesium deficiency? Br J Clin Pharmacol 1993;36:1–10pmid:8373706
    OpenUrlCrossRefPubMedWeb of Science
  107. ↵
    1. Ishii M,
    2. Horio Y,
    3. Tada Y, et al
    . Expression and clustered distribution of an inwardly rectifying potassium channel, KAB-2/Kir4.1, on mammalian retinal Müller cell membrane: their regulation by insulin and laminin signals. J Neurosci 1997;17:7725–7735pmid:9315894
    OpenUrlAbstract/FREE Full Text
  108. ↵
    1. Zhang Y,
    2. Xu G,
    3. Ling Q,
    4. Da C
    . Expression of aquaporin 4 and Kir4.1 in diabetic rat retina: treatment with minocycline. J Int Med Res 2011;39:464–479pmid:21672350
    OpenUrlAbstract/FREE Full Text
  109. ↵
    1. Bockenhauer D,
    2. Feather S,
    3. Stanescu HC, et al
    . Epilepsy, ataxia, sensorineural deafness, tubulopathy, and KCNJ10 mutations. N Engl J Med 2009;360:1960–1970pmid:19420365
    OpenUrlCrossRefPubMedWeb of Science
  110. ↵
    1. Scholl UI,
    2. Choi M,
    3. Liu T, et al
    . Seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance (SeSAME syndrome) caused by mutations in KCNJ10. Proc Natl Acad Sci U S A 2009;106:5842–5847pmid:19289823
    OpenUrlAbstract/FREE Full Text
  111. ↵
    1. Galuska D,
    2. Kotova O,
    3. Barrès R,
    4. Chibalina D,
    5. Benziane B,
    6. Chibalin AV
    . Altered expression and insulin-induced trafficking of Na+-K+-ATPase in rat skeletal muscle: effects of high-fat diet and exercise. Am J Physiol Endocrinol Metab 2009;297:E38–E49pmid:19366873
    OpenUrlAbstract/FREE Full Text
  112. ↵
    1. Rosta K,
    2. Tulassay E,
    3. Enzsoly A, et al
    . Insulin induced translocation of Na+/K+ -ATPase is decreased in the heart of streptozotocin diabetic rats. Acta Pharmacol Sin 2009;30:1616–1624pmid:19915586
    OpenUrlCrossRefPubMed
  113. ↵
    1. Vague P,
    2. Coste TC,
    3. Jannot MF,
    4. Raccah D,
    5. Tsimaratos M
    . C-peptide, Na+,K(+)-ATPase, and diabetes. Exp Diabesity Res 2004;5:37–50pmid:15198370
    OpenUrlCrossRefPubMedWeb of Science
  114. ↵
    1. Sweeney G,
    2. Klip A
    . Regulation of the Na+/K+-ATPase by insulin: why and how? Mol Cell Biochem 1998;182:121–133pmid:9609121
    OpenUrlCrossRefPubMedWeb of Science
  115. ↵
    Alves DS, Thulin G, Loffing J, Kashgarian M, Caplan MJ. Akt substrate of 160 kD regulates Na+,K+-ATPase trafficking in response to energy depletion and renal ischemia. J Am Soc Nephrol 2015;26:2765–2776
  116. ↵
    1. Lennon EJ,
    2. Lemann J Jr.,
    3. Piering WF,
    4. Larson LS
    . The effect of glucose on urinary cation excretion during chronic extracellular volume expansion in normal man. J Clin Invest 1974;53:1424–1433pmid:4825233
    OpenUrlCrossRefPubMedWeb of Science
  117. ↵
    1. Roy DR,
    2. Seely JF
    . Effect of glucose on renal excretion of electrolytes in the rat. Am J Physiol 1981;240:F17–F24pmid:7006416
    OpenUrlPubMed
  118. ↵
    1. Ly JP,
    2. Onay T,
    3. Sison K, et al
    . The Sweet Pee model for Sglt2 mutation. J Am Soc Nephrol 2011;22:113–123pmid:21209254
    OpenUrlAbstract/FREE Full Text
  119. ↵
    1. Cherney DZ,
    2. Perkins BA,
    3. Soleymanlou N, et al
    . Renal hemodynamic effect of sodium-glucose cotransporter 2 inhibition in patients with type 1 diabetes mellitus. Circulation 2014;129:587–597pmid:24334175
    OpenUrlAbstract/FREE Full Text
  120. ↵
    1. Ferrannini E,
    2. Ramos SJ,
    3. Salsali A,
    4. Tang W,
    5. List JF
    . Dapagliflozin monotherapy in type 2 diabetic patients with inadequate glycemic control by diet and exercise: a randomized, double-blind, placebo-controlled, phase 3 trial. Diabetes Care 2010;33:2217–2224pmid:20566676
    OpenUrlAbstract/FREE Full Text
  121. ↵
    1. Ahloulay M,
    2. Schmitt F,
    3. Déchaux M,
    4. Bankir L
    . Vasopressin and urinary concentrating activity in diabetes mellitus. Diabetes Metab 1999;25:213–222pmid:10499190
    OpenUrlPubMedWeb of Science
  122. ↵
    1. Premaratne E,
    2. Verma S,
    3. Ekinci EI,
    4. Theverkalam G,
    5. Jerums G,
    6. MacIsaac RJ
    . The impact of hyperfiltration on the diabetic kidney. Diabetes Metab 2015;41:5–17pmid:25457474
    OpenUrlCrossRefPubMed
  123. ↵
    1. Le Grimellec C
    . Micropuncture study along the proximal convoluted tubule. Electrolyte reabsorption in first convolutions. Pflugers Arch 1975;354:133–150pmid:1167675
    OpenUrlCrossRefPubMed
  124. ↵
    1. Singh DK,
    2. Winocour P,
    3. Farrington K
    . Oxidative stress in early diabetic nephropathy: fueling the fire. Nat Rev Endocrinol 2011;7:176–184pmid:21151200
    OpenUrlCrossRefPubMed
  125. ↵
    1. Cao G,
    2. Lee KP,
    3. van der Wijst J, et al
    . Methionine sulfoxide reductase B1 (MsrB1) recovers TRPM6 channel activity during oxidative stress. J Biol Chem 2010;285:26081–26087pmid:20584906
    OpenUrlAbstract/FREE Full Text
  126. ↵
    1. Li Y,
    2. Zhang W,
    3. Li P,
    4. Huang K
    . Effect of streptozocin-induced diabetes mellitus on expression of methionine sulfoxide reductases and accumulation of their substrates in mouse lenses. Exp Eye Res 2011;92:401–407pmid:21362417
    OpenUrlCrossRefPubMed
  127. ↵
    1. Dasgupta A,
    2. Sarma D,
    3. Saikia UK
    . Hypomagnesemia in type 2 diabetes mellitus. Indian J Endocrinol Metab 2012;16:1000–1003pmid:23226651
    OpenUrlCrossRefPubMed
  128. ↵
    1. Hess MW,
    2. Hoenderop JG,
    3. Bindels RJ,
    4. Drenth JP
    . Systematic review: hypomagnesaemia induced by proton pump inhibition. Aliment Pharmacol Ther 2012;36:405–413pmid:22762246
    OpenUrlCrossRefPubMed
  129. ↵
    Lameris AL, Monnens LA, Bindels RJ, Hoenderop JG. Drug-induced alterations in Mg2+ homoeostasis. Clin Sci (Lond) 2012;123:1–14
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Hypomagnesemia in Type 2 Diabetes: A Vicious Circle?
Lisanne M.M. Gommers, Joost G.J. Hoenderop, René J.M. Bindels, Jeroen H.F. de Baaij
Diabetes Jan 2016, 65 (1) 3-13; DOI: 10.2337/db15-1028
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