Chromium supplementation does not improve glucose tolerance, insulin sensitivity, or lipid profile: a randomized, placebo-controlled, double-blind trial of supplementation in subjects with impaired glucose tolerance.

Chromium supplements are thought to be the second most commonly taken nutritional supplement, used by an estimated 10 million Americans (1). Chromium is an essential element in humans, and deficiency is associated with the development of diabetes, which was first noted in patients receiving long-term parenteral nutrition before the advent of routine chromium supplementation (2,3). In these patients, diabetes resolved following chromium replacement (2–4). The dietary requirement for chromium is controversial, with the recommended daily intake in the U.S. being 0.05–0.20 g (5). Chromium is abundant in the environment; however, aside from the extreme situation of unsupplemented parenteral nutrition, it has proven difficult to ascertain any clinical effects, due solely to chromium deficiency. Despite these difficulties, chromium supplements are widely promoted in the complementary health industries. There are many studies examining the effects of various forms of chromium supplementation (rev. in 6,7). These studies utilized a variety of chromium formulations, varying doses, and patients with normal glucose tolerance, diabetes, or gestational diabetes. The outcomes have been inconsistent. Some studies showed no benefit, and other studies have shown inconsistent improvements in glucose, insulin resistance, and/or lipids. The paucity of data has prompted the National Institutes of Health to release a program announcement to address the issue: “Chromium as an adjuvant therapy for type 2 diabetes and impaired glucose tolerance.” This randomized, placebo-controlled, double-blind study was performed to examine the effect of chromium picolinate supplementation on glucose tolerance, insulin resistance, and lipids in patients with impaired glucose tolerance (IGT).