Glucose Tolerance in Zinc-deficient Rats

Abstract

Two experiments were conducted to determine the effect of zinc deficiency on glucose tolerance (GT) in the rat. In experiment 1, twenty-four male rats initially weighing 200 g were fed low zinc (1.5 ppm Zn) or zinc-supple mented (50 ppm Zn) diets. An abnormal elevation in blood glucose was observed, in the rats fed the low zinc diet, following the second of two intraperitoneal (IP) glucose doses administered 2 hours apart. The blood glucose levels in zinc- deficient and zinc-supplemented rats were not significantly different when the glucose dose was administered orally. In experiment 2, twenty-four weanling female rats were fed the low zinc or zinc-supplemented diets. As soon as an im paired GT to a second IP glucose dose was observed, six zinc-deficient rats were switched to the supplemented diet and pair-fed to the remaining six deficient rats. These rats had a normal GT within 1 week. The six zinc-supplemented rats, which were switched to the deficient diet, had a GT which was no different from their pair-fed zinc-supplemented mates for at least 3 weeks. These studies show that zinc-deficient rats have a significantly (P<0.01) abnormal GT to an IP glucose dose but not to an oral dose. Zinc supplementation corrects the GT im pairment within 1 week. J. Nutr. 702: 1079-1084, 1972.