TABLE 4

Quantitative metabolic traits during an IVGTT followed by a hyperinsulinemic-euglycemic clamp in the population-based sample of 77 elderly Danish twins stratified according to MTNR1B rs10830963 genotype

rs10830963CCCGGGEffect per allele (95% CI)Padd
n (men/women)38 (20/18)36 (13/23)3 (0/3)
Age (years)62 ± 262 ± 262 ± 2
BMI (kg/m2)27.5 ± 4.225.3 ± 4.522.0 ± 0.9−2.5 (−4.4 to −0.6)0.015
Plasma glucose (mmol/l)
    Fasting5.8 ± 1.25.5 ± 1.16.3 ± 1.2−0.06 (−0.4 to 0.3)0.72
    10 min post-IVGTT14.2 ± 1.213.9 ± 1.115.0 ± 0.50.3 (−0.1 to 0.8)0.15
    30 min post-IVGTT11.2 ± 1.311.1 ± 1.112.0 ± 0.70.5 (0.003 to 1.1)0.055
Plasma insulin (pmol/l)
    Fasting34 (19–52)24 (16–34)19 (19–21)−0.03 (−0.2 to 0.2)0.74
    10 min post-IVGTT165 (111–288)94 (67–125)86 (37–98)−0.3 (−0.7 to 0.03)0.075
    30 min post-IVGTT108 (71–170)75 (55–96)63 (29–82)−0.3 (−0.5 to −0.03)0.035
Acute serum insulin response 0–10 min (pmol/l × min)1,802 (1,389–3,724)1,144 (739–1,690)855 (99–1,433)−0.5 (−0.9 to −0.2)0.0077
Basal (mg × kg−1× min−1)
    Hepatic glucose production3.1 ± 0.43.0 ± 0.33.2 ± 0.8−0.1 (−0.3 to 0.03)0.13
Clamp (mg × kg−1× min−1)
    Glucose disposal rate (Rd)9.0 ± 3.39.8 ± 2.715.7 ± 3.61.0 (−0.4 to 2.2)0.18
    Hepatic glucose production1.5 ± 0.71.7 ± 0.52.9 ± 1.70.4 (0.07 to 0.6)0.017
  • Data are means ± SD or medians (interquartile range) (values of plasma insulin and acute serum insulin response). Hepatic glucose production and glucose disposal rates are expressed as mg · kg body mass−1 · min−1in the fasting state and during insulin infusion. Values of plasma insulin were logarithmically transformed before statistical analysis, and their effect sizes are presented as the increase/decrease in percent. P values and effect sizes were calculated using a mixed model adjusted for sex, age, and BMI. The additive model includes a random-effects term for twin pair membership and a fixed-effects term for zygosity. Acute serum insulin response 0–10 min, hepatic glucose production, and glucose disposal rate are calculated as described elsewhere (18) and in the online appendix.