Abstract and Introduction
Abstract
Objective: The aim of this study was to examine the relationship between type 1 and type 2 diabetes and risk of stroke subtypes in women.
Research Design and Methods: We followed 116,316 women aged 30–55 years in 1976 through 2002 for incidence of stroke. At baseline and through biennial follow-up, women were asked about their history and treatment of diabetes and other potential risk factors for stroke.
Results: During 2.87 million person-years of follow-up, 3,463 incident strokes occurred. In multivariate analyses, the incidence of total stroke was fourfold higher in women with type 1 diabetes (relative risk [RR] 4.7 [95% CI 3.3–6.6]) and twofold higher among women with type 2 diabetes (1.8 [1.7–2.0]) than for nondiabetic women. The multivariate RR of ischemic stroke was increased sixfold (6.3 [4.0–9.8]) in type 1 diabetes and twofold (2.3 [2.0–2.6]) in type 2 diabetes. Risks for large-artery infarction and lacunar stroke were similar. Type 1 diabetes was also significantly associated with the risk of hemorrhagic stroke (3.8 [1.2–11.8]), but type 2 diabetes was not (1.0 [0.7–1.4]).
Conclusions: Both type 1 and type 2 diabetes are associated with substantially increased risks of total and most subtypes of stroke.
Introduction
In many but not all epidemiological studies, type 2 diabetes has been an important risk factor for ischemic stroke; however, relative risks (RRs) have varied widely, from 1.3 to 4.9. The disparate RRs may be explained in part by differences in populations, definitions of diabetes, types of stroke studied, and analytical methods. The increased risk of stroke has been linked to the pathophysiological changes seen in the cerebral vessels of individuals with diabetes. In contrast, the association with hemorrhagic stroke remains controversial; reported associations have been positive, null, or even inverse. Further, only a few small studies have examined the risk of stroke in patients with type 1 diabetes, and this relationship remains unsettled. We used the large ongoing Nurses' Health Study to examine the risk of total stroke and its subtypes in women with type 1 or type 2 diabetes.