Effects of zinc gluconate on copper, iron and calcium levels in patients with type 2 diabetes mellitus

Z Stanojevic1, R Mitic1, D Valjarevic2, M Stanic3, Z Bukumiric4. 1Medical Faculty Pristina in Kosovska Mitrovica, Institute of Pharmacology and Toxicology 38220, Serbia, 2Faculty of Natural Sciences and mathematics Pristina in Kosovska Mitrovica, Department of mathematics 38220, Serbia, 3Medical Centre Kosovska Mitrovica, Biochemical-Clinical Laboratory 38220, Serbia, 4Medical Faculty Pristina in Kosovska Mitrovica, Institute of Medical Statistics and Informatics 38220, Serbia

Introduction Zinc, chromium, copper and selenium are having a special role in preventing micro- and macrovascular diabetic complications, as integral components of antioxidant enzymes and also as cofactor of enzymes and hormons involved in the metabolism of glucose and lipid. It is known that zinc compete with another elements such as cadmium, cooper, lead, iron and calcium for the similar binding site. The aim of this study was to evaluate the effects of different doses of zinc gluconate on copper, iron and calcium levels in the serum of patients with type 2 diabetes mellitus and healthy subjects. Methods We studied 12 subjects with type 2 diabetes mellitus and 12 healthy individuals. All participants had not taken vitamin or mineral supplements for at least 3 months before sampling. Blood samples were drawn after an overnight fasting in both groups, before and 24 hour after zinc gluconate supplementation in three different single doses (15, 25 and 50 mg) with washout period (10 t1/2) between treatments. Serum concentration of zinc and copper were measured by Randox colorimetric assays. Serum iron and calcium levels were measured by colorimetric method (Roche Diagnostics). Results Different doses of zinc gluconate did not cause any significant change on copper, iron and calcium levels in the serum of healthy subjects 24 hour after zinc supplementation compared with the value obtained before treatment. The calcium concentration, however, were found to be significant decreased 24 hour after zinc supplementation in dose of 50 mg in patients with type 2 diabetes mellitus compared with the value marked before treatment (p<0,05). The Cu/Zn ratio were significantly lower in diabetic patients 24 hour after zinc supplementation in doses of 25 and 50 mg compared with initial values marked before administration (p<0,05). The Fe/Zn ratio, on the other hand, was not different in diabetics and healthy subjects. As expected Cu/Zn ratio negatively correlated with zinc concentration and positively correlated with copper level in serum. Conclusions The administration of zinc gluconate in single higher doses showed reduction of calcium level in serum and Cu/Zn ratio only in type 2 diabetic patients.