Vitamin D Inadequacy is Associated With Incidence of Type 2 Diabetes

Emerging evidence suggests that vitamin D [25-hydroxyvitamin D; 25(OH)D] may play a role in the etiology of type 2 diabetes. Vitamin D levels are lower in those with type 2 diabetes and impaired glucose tolerance (IGT) compared with those with normal glucose tolerance (NGT). In addition, a few prospective studies have shown a significant inverse association of baseline serum 25(OH)D with incident diabetes. To date, however, the exact mechanisms through which vitamin D affects diabetes risk are not yet fully known, particularly whether vitamin D plays a role in insulin resistance (IR) and/or b-cell dysfunction, the main pathophysiological disorders underlying type 2 diabetes. So, the investigators plan to examine the prospective associations of baseline vitamin D [25-hydroxyvitamin D; 25(OH)D] with insulin resistance (IR), b-cell function, and glucose homeostasis in subjects at risk for type 2 diabetes.