Short-term zinc supplementation in women with non-insulin-dependent diabetes mellitus: effects on plasma 5'-nucleotidase activities, insulin-like growth factor I concentrations, and lipoprotein oxidation rates in vitro

Abstract

Non-insulin-dependent diabetes mellitus (NIDDM) may cause vulnerability to moderate zinc deficiency. In this study, short-term zinc supplementation (30 mg/d as amino acid chelate for 3 wk) elevated plasma zinc and activities of 5'-nucleotidase, a zinc-dependant enzyme, in 20 postmenopausal women with NIDDM. Placebo, given to 20 other women with NIDDM, had no effects on these indexes nor on any others taken in this study. Although zinc supplementation doubled the mean value for 5'-nucleotidase activity, values were still significantly lower than those of age-matched control subjects. Plasma insulin-like growth factor I concentrations increased with zinc treatment if starting concentrations were < 165 microg/L but were unchanged if they were > 165 microg/L. Lipoprotein oxidation in vitro, which has abnormal lag times and propagation rates for subjects with NIDDM and for moderately zinc-deficient rats, were unchanged by zinc supplementation. Possibly, this lack of effect occurred because the zinc treatment did not normalize zinc status. In conclusion, this study supports the contention that moderate zinc deficiency occurs frequently in subjects with NIDDM.