Short title: SERUM MANGANESE IN DIABETES MELLITUS Key words: diabetes mellitus, manganese, children, microvascular complications

Type 1 (insulin dependent) diabetes mellitus is an autoimmune disease leading to the development of diabetic vascular complications. The aim of the study was to investigate the correlation between serum manganese concentration and development of microvascular complications in diabetic children. The manganese concentration was measured by a highly sensitive catalytic method. The study included 59 diabetic children (mean age 13.2±3.3 years, diabetes duration 7.1±2.1 years), 25 of them with microvascular complications (group 1) and 34 without microvascular complications (group 2). Control group included 17 healthy children (mean age 13.1±4.1 years). Diabetic children showed statistically nonsignificantly higher manganese concentrations than control subjects (0.67±0.14 vs. 0.64±0.12 ng/ml; p>0.05). Group 1 showed statistically significant lower concentrations than controls (0.57±0.09 vs. 0.64±0.12 ng/ml; p=0.045). Group 2 showed nonsignificantly higher manganese concentrations than controls (0.69±0.10 vs. 0.64±0.12 ng/ml; p=0.157). Manganese concentration correlated with HbA1c (r=0.45; p=0.008), microvascular complications (r=0.40, p=0.04), and diabetes duration (r=0.48, p=0.03). We suggest that decreased manganese concentrations are associated with the development of microvascular complications in diabetic children.