Impaired insulin sensitivity among nondiabetic patients with a recent TIA or ischemic stroke

OBJECTIVES: To determine the prevalence of impaired insulin sensitivity among nondiabetic patients with a recent TIA or nondisabling ischemic stroke. METHODS: Eligible subjects were nondiabetic men and women over age 45 years who were hospitalized with a TIA or ischemic stroke. To measure insulin sensitivity, subjects underwent an oral glucose tolerance test between 2 and 6 months after their event. Impaired insulin sensitivity was defined by a value of < or =2.5 on the Composite Insulin Sensitivity Index derived from insulin and glucose values during the test. RESULTS: Between July 2000 and June 2001, we identified 177 eligible patients, among whom 105 declined to participate and 72 enrolled. The median age of participants was 71 years and 46 (64%) were men. The baseline event was stroke for 57 subjects (79%). A history of myocardial infarction (MI) was reported by 14 subjects (19%), and 16 (22%) were obese (body mass index > 30). Fasting glucose was normal (<110 mg/dL) for 58 (80%) participants and impaired (110 to 125 mg/dL) for 14 (20%). Among 72 participants, the median insulin sensitivity index value was 2.6 (range 0.9 to 10.2). The prevalence of impaired insulin sensitivity was 36 of 72 (50%, 95% CI 38% to 62%). Impaired insulin sensitivity was more prevalent among younger patients and patients with obesity, lacunar stroke etiology, and disability (Rankin grade >1). CONCLUSION: Impaired insulin sensitivity is highly prevalent among nondiabetic patients with a recent TIA or nondisabling ischemic stroke. This finding has important therapeutic implications if treatment to improve insulin sensitivity is shown to reduce risk for subsequent stroke and heart disease.