Evidence from trials with vitamin D and /or calcium supplementation suggests that combined vitamin D and calcium supplementation may have a role in the prevention of type 2 DM only in population s at high risk ( i.e. glucose intolerance ) .
Vitamin D and calcium insufficiency may negatively influence glycemia , whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism
CONTEXT Altered vitamin D and calcium homeostasis may play a role in the development of type 2 diabetes mellitus ( type 2 DM ) .
No effect of calcitriol on insulin-mediated glucose uptake in healthy subjects.
Administration of active vitamin D ( calcitriol ) improves insulin sensitivity in uraemic patients . These patients have subnormal plasma calcitriol concentrations in parallel with increased intact parathyroid hormone ( PTH ) concentrations . It is therefore unclear whether the improvement in insulin sensitivity results from a direct effect of calcitriol or from amelioration of secondary hyperparathyroidism . So far , no evidence has been presented that insulin sensitivity is specifically affected by calcitriol in healthy subjects . We investigated the effect of (supra)therapeutic doses of calcitriol on insulin sensitivity in healthy volunteers . In a double-blind parallel group design , 18 healthy male subjects received in r and om order either placebo or 1.5 micrograms of calcitriol per day by mouth for 7 days . Insulin-mediated glucose uptake , i.e. insulin sensitivity , was assessed using the euglycaemic clamp technique . Mean glucose disposal rate , i.e. M-value , was not significantly affected by placebo or calcitriol treatment ( placebo : 7.1 + /- 1.3 mg kg-1 min-1 before and 7.2 + /- 1.5 mg kg-1 min-1 after treatment ; calcitriol 7.0 + /- 1.4 mg kg-1 min-1 and 7.2 + /- 1.4 mg kg-1 min-1 ) . There were no significant changes in mean plasma glucose , insulin , phosphate , bicarbonate and ionized calcium concentrations after administration of placebo or calcitriol . Furthermore , platelet intracellular calcium concentration ( assessed by fluorescence spectroscopy ) and mean arterial blood pressure ( 24 h ambulatory measurement ) did not change with placebo and calcitriol treatment . On the other h and , mean intact PTH concentration decreased significantly ( P < 0.01 ) with calcitriol treatment , but not with placebo . In addition , mean 24 h urinary calcium excretion increased significantly ( P < 0.05 ) with calcitriol administration but was unchanged with placebo . Administration of (supra)physiological doses of calcitriol has no effect on insulin sensitivity in healthy subjects , despite a significant decrease in PTH concentrations . These observations are compatible with the notion that the effect of calcitriol on insulin sensitivity is present only in uraemic calcitriol-depleted patients
Evidence from trials with vitamin D and /or calcium supplementation suggests that combined vitamin D and calcium supplementation may have a role in the prevention of type 2 DM only in population s at high risk ( i.e. glucose intolerance ) .
Vitamin D and calcium insufficiency may negatively influence glycemia , whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism
CONTEXT Altered vitamin D and calcium homeostasis may play a role in the development of type 2 diabetes mellitus ( type 2 DM ) .