GLYCEMIC CONTROL AND DEVELOPMENT OF RETINOPATHY IN TYPE-2 DIABETES-MELLITUS - A LONGITUDINAL-STUDY

Relationships between glycaemic control, hypertension, and development of microangiopathy have been well documented in Type 1 (insulin-depen dent) but not in Type 2 (noninsulin-dependent) diabetes mellitus. Ther efore, we have investigated these relationships in a cohort of 64 Type 2 patients free of retinopathy (by angiofluorography), who were regul arly followed until development of retinopathy or for at least 7 years as outpatients. Glycaemic control was assessed by 1 to 4 HbA(1) deter minations per year. Retinal status was monitored by annual angiofluoro graphy. Nonproliferative retinopathy developed in 14 patients (cumulat ive incidence at 13 years: 29.8 %) after a mean diabetes duration of 1 4.3 +/- 8.9 years (range 2-27). In multivariate analysis (Cox model), mean HbA(1) during follow-up (p < 0.001), and hypertension at first ex amination (p = 0.09) were associated with the development of retinopat hy, but age, sex, BMI, diabetes duration, smoking, and fasting blood g lucose were not. The relative risk for developing retinopathy (RR) was 7.2 (IC 95 %: 1.61-32.4) in patients with a mean HbA(1) during follow -up above the median value of the cohort (8.3 %) compared with patient s with HbA(1) during follow-up below this value. RR was 2.5 (IC 0.8-8) in patients with HbA(1) at first examination above compared to below the median value (8.4 %). RR was 3.0 (IC 0.9-10) in patients treated f or hypertension at baseline compared to those without treatment. A six fold increase in retinopathy prevalence was observed between patients with mean HbA(1) in the highest or lowest quartile of mean HbA(1) dist ribution during follow-up. This longitudinal study indicates a strong association between long-term glycaemic control and the development of diabetic retinopathy in Type 2 diabetes. (C) 1998 John Wiley & Sons, Ltd.