Incidence of Stroke According to Presence of Diabetic Nephropathy and Severe Diabetic Retinopathy in Patients With Type 1 Diabetes

Abstract

OBJECTIVE Type 1 diabetes is associated with a markedly increased risk of stroke, but only a few studies on the incidence of stroke in type 1 diabetes exist. Therefore, we assessed the incidence of stroke in patients with type 1 diabetes and studied the impact of diabetic nephropathy (DN) and severe diabetic retinopathy (SDR) on this risk. RESEARCH DESIGN AND METHODS We studied 4,083 patients with type 1 diabetes from the Finnish Diabetic Nephropathy Study. Mean age was 37.4 ± 11.8 years, duration of diabetes was 21.6 ± 12.1 years, and 52% were men. Strokes were identified from medical records, death certificates, and the National Hospital Discharge Register and classified based on medical files and brain images. RESULTS During 36,680 person-years of follow-up, 149 (4%) patients suffered an incident stroke (105 infarctions and 44 hemorrhages). Of the infarctions, 58 (55%) were lacunar. The incidence of stroke, cerebral infarction, and cerebral hemorrhage was 406 (95% CI 344–477), 286 (234–347), and 120 (87–161) per 100,000 person-years, respectively. In an adjusted analysis, microalbuminuria increased the risk of stroke with a hazard ratio (HR) of 3.2 (1.9–5.6), macroalbuminuria 4.9 (2.9–8.2), and end-stage renal disease 7.5 (4.2–13.3), and SDR increased the risk with an HR of 3.0 (1.9–4.5). The risk of cerebral infarction, cerebral hemorrhage, and lacunar infarction increased in a similar manner. The proportion of lacunar versus nonlacunar infarction did not change across DN groups. CONCLUSIONS The presence of SDR and DN, independently, increases the risk of stroke, cerebral infarction, and cerebral hemorrhage in patients with type 1 diabetes.