High prevalence of diabetic retinopathy and nephropathy in polynesians of Western Samoa

OBJECTIVE - To determine the prevalence of diabetic retinopathy and nephropathy and to define associated risk factors in Polynesian Western Samoans with non-insulin-dependent diabetes mellitus (NIDDM) or impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS - A 1991 population- based study in Samoan adult (ages 25-74 years) included a 75-g oral glucose tolerance test, anthropometric measurements, and blood pressure recordings. Subjects with NIDDM or IGT had 45-degree stereo photographs taken (n = 263) (three standard fields of the right eye), and retinopathy was graded in comparison with Airlie House photographs. First-morning urine samples (n = 304) were also collected from these subjects and from a subsample with normal glucose tolerance. Urinary albumin concentration (UAC) was measured by radioimmunoassay microalbuminuria was defined as UAC of 30-299 μg/ml; and macroalbuminuria was defined as UAC ≥300 μg/ml. RESULTS - The prevalence of diabetic retinopathy was 43.2% among subjects with known diabetes and 15.4% in those newly diagnosed. Proliferative diabetic retinopathy was found in 4.5% of known diabetic subjects. The prevalence of elevated UAC was 15.0% in subjects with IGI, 26.0% in newly diagnosed diabetes subjects, and 23.4% in known diabetes subjects. For all diabetic subjects (n = 162), the factors independently associated with diabetic retinopathy (logistic regression) were duration of diabetes, fasting plasma glucose, and body mass index (inversely). Duration of diabetes, serum triglyceride concentrations, and systolic blood pressure were independently associated with elevated UAC in all diabetic subjects (n = 138), and fasting plasma glucose had borderline significance. CONCLUSIONS - Diabetic retinopathy and albuminuria are common in Polynesian Western Samoans. Duration of diabetes and level of glycemia were the most important associated factors. These data underline the need for cost-effective programs for the detection and early treatment of diabetes in Western Samoa and other developing populations with high susceptibility to NIDDM.