Oral glucose tolerance is unaltered in vitamin D-deficient rat.

Vitamin D deficiency has been reported to result in impaired glucose tolerance and decreased insulin secretion when glucose is administered either intravenously or intraperitoneally. The aim of the present study was to study oral glucose tolerance and glucose absorption in a vitamin D-deficient rat model. Oral glucose tolerance tests were carried out in vitamin D-deficient and control rats, and this was found to be unaltered in the deficient state. Intestinal absorption of glucose was drastically reduced in the deficient animal and was found to be due to a reduction in the sodium-dependent component of glucose transport. Thus the unaltered oral glucose tolerance in the vitamin D-deficient rat is probably due to impaired absorption of glucose.