The Effect of Vitamin D Supplementation on Glucose Homeostasis among African Americans and Hispanics with Type 2 Diabetes

The aim of the present study is to determine the effect of supplemental vitamin D intake (4000 IU or 6000 IU of cholecalciferol daily for 6 months) on fasting plasma glucose, fasting insulin, and glycosylated hemoglobin (A1C) in a sample of African Americans and Hispanics with type 2 diabetes and vitamin D insufficiency. Seventy five participants were recruited by community outreach. Plasma glucose concentration was measured by hexokinase enzymatic method. A1C was measured by the DCA2000+ system. Insulin in fasting blood was determined by radioimmunoassay. Serum vitamin D concentrations were measured with an enzyme‐immunoassay kit. General lineal model was used to compare treatment effects and Bonferroni multiple comparison tests was used to detect significant changes from baseline, 3 months, and 6 months on the outcome variables. No significant changes were observed for fasting plasma glucose, insulin or A1C between groups and within groups. Vitamin D supplementation did not improve glucose homeostasis in this sample. Funding for this research was provided through an NIH/NIDDK sponsored grant.