Vitamin D-3, via its active metabolite 1 alpha,25-dihydroxyvitamin D-3, hel
ps maintain normal calcium levels in the body Apart from the maintenance of
calcium homeostasis, the active form of vitamin D-3 is now known to be inv
olved in a number of other functions including that of pancreatic beta cell
s. Low serum insulin levels and impaired glucose tolerance in a vitamin D-d
eficient state have been reported in experimental animals Hypocalcemia is a
major consequence of vitamin D deficiency Whether the impairment observed
is due to vitamin D deficiency per se or is secondary to low calcium is sti
ll a matter of controversy. The present study was conducted to delineate th
e roles of vitamin D and calcium in glucose intolerance associated with vit
amin D deficiency in vivo. It was found that supplementation with either vi
tamin D-3 or high calcium alone to vitamin D-deficient rats could correct t
he defects. In addition, insulin sensitivity was found to be enhanced in th
e vitamin D-deficient group compared with vitamin D control or calcium-supp
lemented groups. Hence the present study demonstrates that calcium per se i
n the absence of vitamin D increases insulin secreation and normalizes into
lerance to glucose seen in vitamin D deficiency. (C) Elsevier Science Inc.
2000. All rights reserved.