Incidence, risk factors, and prognosis of stroke in people with type 1 diabetes

Background: Type 1 diabetes is a chronic condition that increases the risk of stroke. Yet, only a few prior studies have investigated the incidence and risk factors associated with stroke and its subtypes in individuals with type 1 diabetes. Furthermore, the predictors of survival following a stroke remain unclear. Aim: This study sought to examine the incidence and risk factors associated with stroke in individuals with type 1 diabetes. It also sought to elucidate the prognosis and related predictors following an incident stroke in individuals with type 1 diabetes. Participants and methods: This study was conducted as part of the nationwide, multicenter FinnDiane Study, which aims to discover the genetic, environmental, and clinical risk factors associated with diabetic complications in individuals with type 1 diabetes. The population for Studies I, II, and IV comprised 4,083 participants with type 1 diabetes, of whom 149 suffered an incident stroke. The population for Study III comprised 4,105 participants with type 1 diabetes, of whom 202 suffered an incident stroke. All four studies were observational follow-up studies. All the included participants were examined according to the same examination protocol. The participants’ strokes were classified into different subtypes based on their medical files and brain images. Results: The incidence of stroke and its subtypes (i.e., ischemic stroke, lacunar infarction, and hemorrhagic stroke) increased with the presence of both severe diabetic retinopathy and advancing diabetic kidney disease. A long duration of diabetes, poor glycemic control, high systolic blood pressure, and a history of smoking were all independent risk factors for ischemic stroke, while high systolic blood pressure and a lower body mass index increased the risk of hemorrhagic stroke, along with severe diabetic retinopathy and diabetic kidney disease. The risk of stroke increased in a linear fashion with increasing blood pressure. The overall likelihood of survival following an incident stroke was poor, and 53% of the participants died during the mean follow-up period of 3.4 years. The predictors of a worse outcome were stroke of hemorrhagic origin, worsening kidney function, and the presence of kidney replacement therapy. Conclusions: Individuals with type 1 diabetes, who suffer a stroke, are generally of poor health and suffer from diabetic microvascular complications, high blood pressure, and poor glycemic control. Both elevated systolic blood pressure and diabetic kidney disease represent important risk factors with regard to the development of stroke. The prognosis following a stroke is poor in individuals with type 1 diabetes, and the presence of diabetic kidney disease has a substantially negative impact on their prognosis. In terms of the prevention and treatment of stroke, it is important to identify these high-risk individuals. This could be achieved through regular measurements of the blood pressure and blood glucose levels of individuals with type 1 diabetes, in addition to screening for early markers of diabetic kidney disease.