Renal handling of zinc in insulin-dependent diabetes mellitus patients

Hyperzincuria is a common feature in diabetic patients, which is still not understood. Based on the above consideration, the aim of the present study was to investigate the renal handling of zinc in insulin-dependent diabetes mellitus (IDDM) patients. The glomerular filtration rate, urinary zinc exc retion, zinc clearance, zinc clearance/creatinine clearance ratio, zinc tub ular reabsorption, glycosuria, plasma glucose, C-peptide, glucagon, and cor tisol were investigated in 10 normal individuals (Group C1 and Group C2, re spectively) and 10 IDDM patients (Group E1: hyperglycemic and glycosuric an d Group E2: normoglycemic and aglycosuric) during placebo or venous zinc to lerance test. The results showed that urinary zinc excretion and renal zinc clearance were increased after zinc injection in normal individuals (Group C2) and IDDM patients (Groups E1 and E2) when compared with normal individ uals-placebo (Group C1). However, these renal parameters were statistically more significant in the hyperglycemic and glycosuric diabetics (Group E1). Because patients in Group E1 had the lowest plasma C-peptide levels and sh owed a strong negative correlation between CZn++/Ccr ratio and this hormone , we suggest that in this setting insulin inhibits urinary zinc excretion.