Abstract: In this study serum copper, chromium and manganese were estimated in 90 diabetic patients attending the outpatient clinic of the Federal Medical Centre, Katsina, an ancient city in North-western Nigeria and the results compared to those of apparently healthy, non-diabetic volunteers of comparable age and social status. Serum glucose level of the diabetic subjects (13.91±2.87 mmol L-1) was significantly (p<0.05) higher that the value obtained for the non-diabetic subjects (4.34±0.11 mmol L-1). The serum levels of Cr (0.19±0.05 μg L-1), Cu (0.42±0.18 μg L-1) and Mn ((1.12±0.24 μg L-1) were significantly (p<0.05) lowered in diabetic subjects. About 75% of the diabetic subjects in the study area had deficient serum levels of these metals. These results suggest that the diabetic patients in the study area have low serum levels of some antioxidant mineral elements. These observations may be an indication that the diabetic subjects are predisposed to increased oxidative onslaught.