A modified frequently sampled intravenous glucose tolerance (mFSIGT) test was used. On day 0, baseline 22 time point mFSIGT was performed. Subjects were then treated with cholecalciferol (vitamin D3) supplementation - 10,000 IU/day - for 28 consecutive days. mFSIGT was then repeated measuring glucose, insulin and c-peptide at all time points. 25-OH vitamin D, PTH, and calcium were also measured at time point 0 pre and post vitamin D supplementation. Data was analyzed using the Bergman/Boston minimal model for insulin homeostasis with MinMod Millennium software.
