The presence of multiple confounders in the study design make these discrepant results difficult to interpret, and importantly, most studies lacked any measurement of serum or urine chromium levels. Results from these studies have been inconclusive, however, with both positive and negative findings – reviewed in. Most of the current knowledge on the effects of chromium on glucose homeostasis comes from clinical studies examining the effect of chromium supplementation on glucose intolerance and insulin resistance. The authors nonetheless postulated that chromium supplementation might be recommended to prevent or delay the progression of insulin resistance into diabetes. ![]() However, with no measures of serum chromium, it was not possible to determine whether increased chromium excretion was a primary defect producing reduced serum chromium, or whether higher excretion resulted from higher serum levels. The investigators hypothesized that higher excretion rates could produce chromium deficiencies that could contribute to insulin resistance. ![]() However, the actual contribution of altered chromium levels to insulin action and glucose homeostasis in humans is not clear.Ī recent study of non-diabetic Saudi men and women reported that insulin resistance in this population was associated with increased urinary excretion of chromium. In the 1970s studies of patients with small bowel syndrome suggested that low chromium levels contributed to glucose intolerance that could be reversed by chromium supplementation. Limited animal data and some in vitro data on myoblasts suggested that chromium is a positive regulator of insulin action. Chromium was identified as the active component in these concentrates. The concept that chromium may have a role in carbohydrate metabolism dates back to the 1950’s with the observation that rats fed a Torula yeast-based diet developed glucose intolerance and that the intolerance was reversed by concentrates prepared from dried Brewer’s yeast and dried porcine kidney powder. In 1996 it was estimated that about 10 million people in the United States took chromium supplements at a cost of $ 150 million dollars per year, largely as a result of claims of beneficial effects on insulin action and glucose tolerance. The study was registered on the NIH registry () and the identifier is NCT00846248Ĭhromium is a very commonly used nutritional supplement. Caution therefore should be exercised in recommending the use of this supplement. Further, subjects who have high serum chromium levels paradoxically had a decline in insulin sensitivity. ConclusionsĬhromium therapy did not improve insulin sensitivity in non-obese normoglycemic individuals. This effect could not be explained by changes in physiological parameters such as body weight, truncal fat and serum lipids with chromium therapy. There was, however, a strong association between serum chromium and change in insulin resistance (β = -0.83, p=0.01), where subjects with the highest serum chromium had a worsening of insulin sensitivity. ![]() ResultsĪfter 16 weeks of chromium picolinate therapy there was no significant change in insulin sensitivity between groups (p=0.83). Pre-specified secondary endpoints included fasting lipids, blood pressure, weight, body composition measured by DXA scan. The primary endpoint was change in insulin sensitivity as measured by euglycemic hyperinsulinemic clamp. After baseline studies, the subjects were randomized to placebo or chromium picolinate 500 μg twice a day. ![]() MethodsĪ double blind placebo-controlled randomized trial was conducted on 31 non-obese, normoglycemic subjects. In the present studies, we test the hypothesis that chromium supplementation raises serum chromium levels and correspondingly improves insulin sensitivity. The use of chromium supplements is widespread for the prevention and treatment of diabetes mellitus but there are conflicting reports on efficacy, possibly reflecting discrepant effects across different populations.
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