Relative chromium response as an indicator of chromium status.

Twenty-seven women ages 40 to 75 were divided into normal (n = 15) and hyperglycemic (n = 12) groups on the basis of 3-hr glucose tolerance tests. Each subject received 5 g of brewer's yeast extract containing 4 microgram of chromium daily for 3 months. Glucose, insulin, and chromium levels were analyzed by oxidase, radioimmunoassay, and radiochemical neutron activation analysis methods, respectively. The fasting and 1-hr serum chromium levels (ng/ml) changed from 1.67 and 1.43 to 1.46 and 1.86 in the normal group, and from 1.89 and 1.03 to 0.94 and 1.03 in the hyperglycemic group. Considerable changes occurred in the relative chromium response (RCR) at the 1-hr point. RCR is defined as (1-hr serum chromium level/fasting serum chromium level) X 100. Among the normal subjects, 73% showed an improved RCR after the supplementation: mean RCR was 107% before and 140% after. Among the hyperglycemic subjects, 75% showed an improved RCR: mean RCR was 81% before and 149% after the supplementation. The increased RCR was associated with decreased serum insulin and glucose levels. This is interpreted as reflecting an improved chromium status for the majority of individuals in both groups after the supplementation. The observations suggest that 1) in response to a glucose load, serum chromium levels drop in subjects with presumably inadequate chromium storage; 2) a low value of relative chromium response at the 1-hr point indicates a suboptimal chromium nutritional status.