PORTAL VEIN GLUCOSE SENSORS DO NOT PLAY A MAJOR ROLE IN MODULATING PHYSIOLOGICAL RESPONSES TO INSULIN-INDUCED HYPOGLYCEMIA IN HUMANS

Abstract

Objective: Experimental data from animal studies indicate that portal vein glucose sensors play a key role in the responses to slow-fall hypoglycemia. However, their role in modulating these responses in humans is not well understood. The aim of the present study was to examine in humans the potential role of portal vein glucose sensors on physiological responses to insulin-induced hypoglycemia mimicking the slow fall of insulin treated diabetic subjects.

Research Design and Methods: 10 nondiabetic subjects were studied on two different occasions during intravenous insulin (2 mU/kg/min) + variable glucose for 160 minutes. In both studies, hypoglycemia (47 mg/dl) was induced slowly (in 60 min) and was followed by clamped H (plasma glucose, PG, 47 mg/dl for 40 min). Hypoglycemia was preceded by the ingestion of either oral placebo (P) or glucose (28g) (GLU) given at +30 min.

Results: PG and insulin were no different both with P and GLU (p>0.2). Similarly, counterregulatory hormones, substrates and symptoms were not different with either P or GLU. The Stroop color and colored words subtest of the Stroop test deteriorated less (P<0.05) with G than P.

Conclusions: In contrast to animals, in humans prevention of portal hypoglycemia with oral glucose from the beginning of insulin-induced slow-fall hypoglycemia has no effect on sympathoadrenal and symptomatic responses to hypoglycemia.