A controlled trial found no benefits from adding chromium, in the form of chromium yeast, to standard therapy in patients with type 2 diabetes. Chromium is known to be an important trace mineral with a role in glucose metabolism, and as a result it is widely touted as supplement with potential benefits for people with diabetes. Previous controlled trials have been equivocal, and systematic results have concluded that the effects of chromium on diabetic control are inconclusive. One form of chromium that was widely used, chromium picolinate, has been banned due to concerns over its toxicity: this study aimed to determine whether an alternative form, chromium-enriched brewers yeast, had any benefits. Patients enrolled were from one area in the Netherlands and had type 2 diabetes moderately-well controlled on oral hypoglycaemic agents. They were randomised to treatment with a supplement containing chromium yeast equivalent to 400micrograms daily or placebo; study duration was six months, and the primary outcome was change in levels of haemoglobin A1c (HbA1c).
A total of 57 patients was randomised, of whom one did not complete the study. In the remainder, there was no difference between the active and placebo groups in the primary outcome, or in any of the secondary outcomes measured. One patient in each group reported adverse effects: nausea with chromium yeast and 'non-specific stomach problems' with the placebo. The authors conclude that chromium supplementation using chromium yeast had no effect on glycaemic control in their population of moderately well controlled Western patients with type 2 diabetes. They note that patients were not selected on the basis of chromium deficiency, as there is currently no consensus on what this might be; they also note that treatment duration was only six months. On the basis of current evidence, however, they suggest that there is no reason to recommend chromium therapy in Western patients treated with oral hypoglycaemic agents or insulin.
Diabetes Care 2007; 30: 1092-6 (link to abstract)