Effect of chromium picolinate on insulin sensitivity in vivo

This study assessed the effect of chromium (Cr) supplementation on insulin sensitivity and body composition in subjects at high risk for Type 2 diabet es because of family history and obesity. Twenty-nine subjects (14 men, 15 women) were evaluated in a double-blind, randomized, placebo-controlled tri al using chromium picolinate (CrPic) (1,000 mu g/day), or placebo for 8 mon ths of study. Clinical and metabolic evaluations consisted of insulin sensi tivity (S-1) and glucose effectiveness (S-g); measurement of glucose tolera nce and insulin response to an oral glucose tolerance test (75 g OGTT); and 24-hour glucose and insulin profiles. Anthropometric measures and magnetic resonance imaging (MRI) assessed abdominal fat distribution. Fasting plasm a glucose and insulin levels and measures of glycemia (glycated hemoglobin and fructosamine) were also assessed. The CrPic group showed a significant increase in insulin sensitivity at midpoint (P < .05) and end of study (P < .005) compared with controls, which had no significant changes. No change in S-g was seen in either group. There was no effect of CrPic on body weigh t, abdominal fat distribution, or body mass index. However, CrPic significa ntly improved insulin sensitivity in these obese subjects with a family his tory of Type 2 diabetes. Improvement in insulin sensitivity without a chang e in body fat distribution suggests that Cr may alter insulin sensitivity i ndependent of a change in weight or body fat percentage, thereby implying a direct effect on muscle insulin action. Definitive double-blinded, placebo -controlled trials are currently being conducted to confirm this observatio n in Type 2 diabetic subjects and evaluate the effects of Cr supplementatio n on insulin action and glycemic control. J. Trace Elem. Exp. Med. 12:71-83 , 1999. (C) 1999 Wiley-Liss, Inc.