Impact of overweight on chronic microvascular complications in type 1 diabetic patients

OBJECTIVE - To investigate a possible association of BMI with retinopathy and neuropathy in type I diabetes. Retinopathy and neuropathy may not only be related to glycemic control and diabetes duration but also to blood pressure and BMI. RESEARCH DESIGN AND METHODS - A total of 592 type I diabetic patients without nephropathy were studied (M/F: 324/268 age: 41 +/- 12 years duration: 19 +/- 11 years HbA(1c) [AlC]: 7.9 +/- 1.1%). Patients were subdivided according to BMI: 168 men and 146 women with BMI < 25 kg/m(2), and 156 men and 122 women with BMI >= 25 kg/m(2). Retinopathy was examined by fundoscopy and neuropathy by electromyography. RESULTS - Hypertension (> 130/85 mmHg) was present in 40%, retinopathy in 53%, and neuropathy in 43% of patients. Overweight subjects had more retinopathy (63 vs, 45%, P < 0.0001, odds ratio [OR] = 2.1) and neuropathy (49 vs. 38%, P = 0.008, OR = 1.6) than normal-weight patients, Patients with retinopathy were older (45 +/- 12 vs. 37 +/- 11 years' P < 0.0001) and had a longer diabetes duration (25 +/- 10 vs. 12 +/- 8 years, P < 0.0001), a higher AlC (8.0 +/- 1.1 vs. 7.7 +/- 1.1%, P = 0.001), and a higher BMI (25.8 +/- 4.1 vs. 24.7 +/- 4.2 kg/m(2), P = 0.001) than individuals without retinopathy. The same results arc found in neuropathy. Logistic regression analysis showed that diabetes duration (P = 0.15, P < 0,0001), blood pressure (P = 0.22, P = 0.0047), and AlC (P = 0.24, P = 0.01), but not BMI, lipid levels, sex, or age, were independent risk factors for retinopathy. Likewise, duration (P = 0.05, P < 0.0001), age (P = 0.04, P = 0.0001), AlC (P = 0.35, P < 0.0001), and sex (P = 0.74, P = 0.0001) but not BMI, lipid levels, or hypertension were independently associated with neuropathy. Men had more neuropathy than women (50 vs. 34%, P < 0.0001, OR = 1.9). Leptin and adiponectin levels did not differ between individuals with or without microvascular complications. CONCLUSIONS - Retinopathy and neuropathy are more prevalent in overweight (BMI >= 25 kg/m(2)) type 1 diabetic subjects, However, logistic regression analysis showed that diabetes duration and AlC remain the main determinants for retinopathy and neuropathy.