Decreased glucose tolerance in two men during experimental copper depletion

The daily dietary copper requirement of two healthy men was found to exceed 0.78 mg in a depeletion experiment. This amount of dietary copper is similar to that in some contemporary diets. Intravenous glucose tolerance tests were done during the control, depletion and repletion phases of the study. In response to copper depletion the ability of these men to clear a glucose load decreased while hematological indices were unchanged. Glucose clearance improved upon repletion with 6 mg of copper per day; some points on these final curves were lower than corresponding points on curves before depletion. Glucose clearance may be a more sensitive index of copper nutriture than are changes in hematology, plasma copper, ceruloplasmin of cholesterol or erythrocyte superoxide dismutase. The results of this experiment are consonant with experiments with animals and may be of importance in the etiology or pathophysiology of mild diabetes mellitus. (author)