Retinopathy and nephropathy in patients with type 1 diabetes four years after a trial of intensive therapy.

Background: Among patients with type 1 diabetes mellitus, intensive therapy (with the aim of achieving near-normal blood glucose and glycosylated hemo globin concentrations) markedly reduces the risk of microvascular complicat ions as compared with conventional therapy. To assess whether these benefit s persist, we compared the effects of former intensive and conventional the rapy on the occurrence and severity of retinopathy and nephropathy for four years after the end of the Diabetes Control and Complications Trial (DCCT) . Methods: At the end of the DCCT, the patients in the conventional-therapy g roup were offered intensive therapy, and the care of all patients was trans ferred to their own physicians. Retinopathy was evaluated on the basis of c entrally graded fundus photographs in 1208 patients during the fourth year after the DCCT ended, and nephropathy was evaluated on the basis of urine s pecimens obtained from 1302 patients during the third or fourth year, appro ximately half of whom were from each treatment group. Results: The difference in the median glycosylated hemoglobin values betwee n the conventional-therapy and intensive-therapy groups during the 6.5 year s of the DCCT (average, 9.1 percent and 7.2 percent, respectively) narrowed during follow-up (median during 4 years, 8.2 percent and 7.9 percent, resp ectively; P<0.001). Nevertheless, the proportion of patients who had worsen ing retinopathy, including proliferative retinopathy, macular edema, and th e need for laser therapy, was lower in the intensive-therapy group than in the conventional-therapy group (odds reduction, 72 percent to 87 percent; P <0.001). The proportion of patients with an increase in urinary albumin exc retion was significantly lower in the intensive-therapy group. Conclusions: The reduction in the risk of progressive retinopathy and nephr opathy resulting from intensive therapy in patients with type 1 diabetes pe rsists for at least four years, despite increasing hyperglycemia. (N Engl J Med 2000;342:381-9.) (C)2000, Massachusetts Medical Society.