Pilot study to evaluate the effect of short-term improvement in vitamin D status on glucose tolerance in patients with type 2 diabetes mellitus.

OBJECTIVE

To study the effect of improvement in vitamin D status on glucose tolerance in Asian Indian patients with moderately controlled type 2 diabetes mellitus (T2DM).

METHODS

This randomized, double-blind, placebo-controlled pilot study was conducted in 28 Asian Indian patients with T2DM. Study participants were randomly assigned to a vitamin D-treated group (group D) or a placebo group (group P). Serum 25-hydroxyvitamin D, hemoglobin A1c, and serum fructosamine levels were measured, and an oral glucose tolerance test (OGTT) was performed in all patients at baseline and 4 weeks after intervention. During the OGTT, plasma glucose and serum insulin levels were measured at 0, 30, 60, 90, and 120 minutes. The unpaired t test was used to compare the groups at baseline and to compare the differences in changes from baseline to 4 weeks between the 2 study groups.

RESULTS

Group D and group P were similar with respect to their fasting plasma glucose and serum insulin concentrations, post-OGTT plasma glucose and serum insulin levels, and hemoglobin A1c and fructosamine values at baseline. Serum 25-hydroxyvitamin D levels increased significantly in group D at 4 weeks. No significant differences were found between the groups at baseline and 4 weeks with respect to serum fructosamine, fasting plasma glucose and serum insulin, post-OGTT plasma glucose and serum insulin levels, and homeostasis model assessment of insulin resistance.

CONCLUSION

In this study, short-term improvement in vitamin D status was not associated with improvement in glucose tolerance, insulin secretion, or insulin sensitivity in Asian Indian patients with moderately controlled T2DM.