Diabetic retinopathy and control of diabetes with special reference to blood glucose levels

Data concerning diabetic retinopathy were collected prospectively in the Diabetes Clinic of the Third Department of Internal Medicine, University of Tokyo, from the beginning of the Clinic in 1957 until 1985. These data are analyzed here. The prevalence and severity of the retinopathy at the initial visit was strongly related to the duration of diabetes before examination. Pretreatment fasting blood glucose levels were also significantly related. During follow-up, the incidence of retinopathy was most strongly influenced by the degree of control of blood glucose, followed by other factors like blood pressure, age at diagnosis, etc. The effectiveness of sulfonylurea on retinopathy was not inferior to insulin so long as good control was obtained. It was deduced from the analysis of the chain of events that dot hemorrhage is the initial component of diabetic retinopathy, followed by hard exudate, blot hemorrhage, soft exudate and proliferative retinopathy. A six-year fluorescein angiography follow-up of well-controlled non-insulin dependent cases with mild retinopathy showed that microaneurysms disappear rapidly during the first year and more slowly thereafter. The avascular areas once formed seem to progress despite the degree of control exerted here. The other Japanese results are discussed.