Zinc status was assessed in 53 diabetic patients: 18 insulin-dependent diabetic patients (IDDM), 22 noninsulin-dependent diabetic patients (NIDDM) treated with oral antidiabetic agents, and 13 insulin-treated, noninsulin-dependent diabetic patients (IRDM). Plasma zinc concentrations were in the usual range for healthy subjects in these three groups (15.3 +/- 0.9 mumol/L). Urinary zinc excretions were elevated in the IDDM group (18.3 +/- 4.1 mumol/24 h; p less than 0.01 vs normal) and in the NIDDM group (17.5 +/- 3.5 mumol/24 h; p less than 0.01 vs normal), but normal in the IRDM group (11.3 +/- 2.4 mumol/24 h). In 14 NIDDM patients treated with transient continuous sc insulin injections, urinary zinc decreased from 16.5 +/- 2.2 mumol/24 h before insulin treatment to 11.5 +/- 0.3 mumol/24 h after insulin treatment without any modification in plasma zinc concentrations.