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 ) .
Effects of vitamin D on insulin and glucagon secretion in non-insulin-dependent diabetes mellitus.
Vitamin D has been shown to increase insulin release from pancreatic islet cells in vitro , and to improve insulin secretion in vitamin D-deficient animals . Few attempts have been made to evaluate this issue directly in humans . We studied 35 otherwise healthy diabetic subjects in the early spring at the seasonal nadir of 25-hydroxyvitamin D [ 25(OH)D ] concentrations ( mean 35 + /- 7 nmol/L ) .  Fasting glucose , insulin , C-peptide , and glucagon concentrations , and their responses to Sustacal stimulation were not related to indexes of mineral metabolism . In 20 subjects , a double-blinded , placebo-controlled , crossover trials of 1,25-dihydroxyvitamin D[1,25](OH)2D ] treatment ( 1 micrograms/d for 4 d ) had no effect on fasting or stimulated glucose , insulin , C-peptide , or glucagon concentrations . However , insulin and C-peptide responses to Sustacal after 1,25(OH)2D treatment were related to duration of diabetes ( r2 = 0.28 , P = 0.052 and r2 = 0.25 , P = 0.002 , respectively ) in that short duration correlated with improvement after 1,25(OH)2D treatment . Hence , vitamin D nutrition , or 1,25(OH)2D therapy , had no major effect on glucose homeostasis in non-insulin-dependent diabetes mellitus
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 ) .