Impact of Overweight on Chronic Microvascular Complications in Type 1 Diabetic Patients

Abstract

OBJECTIVE—To investigate a possible association of BMI with retinopathy and neuropathy in type 1 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 1 diabetic patients without nephropathy were studied (M/F: 324/268; age: 41 ± 12 years; duration: 19 ± 11 years; HbA_1c [A1C]: 7.9 ± 1.1%). Patients were subdivided according to BMI: 168 men and 146 women with BMI <25 kg/m², and 156 men and 122 women with BMI ≥25 kg/m². 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 A1C (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/m², P = 0.001) than individuals without retinopathy. The same results are found in neuropathy. Logistic regression analysis showed that diabetes duration (β = 0.15, P < 0.0001), blood pressure (β = 0.22, P = 0.0047), and A1C (β = 0.24, P = 0.01), but not BMI, lipid levels, sex, or age, were independent risk factors for retinopathy. Likewise, duration (β = 0.05, P < 0.0001), age (β = 0.04, P = 0.0001), A1C (β = 0.35, P < 0.0001), and sex (β = 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/m²) type 1 diabetic subjects. However, logistic regression analysis showed that diabetes duration and A1C remain the main determinants for retinopathy and neuropathy.