BACKGROUND: Clinical evidence has demonstrated that insulin resistance might be an independent risk factor for ischemic stroke, which has not been recognized. At present, insulin resistance has been proven to be an independent risk factor for coronary arteriosclerotic heart disease. However, the relationship between the onset and prognosis of ischemic stroke remains unclear. OBJECTIVE: This study was designed to analyze the relationship between insulin resistance and ischemic stroke and the correlation between insulin resistance and stroke risk factor, and to investigate the relationship between insulin resistance and ischemic stroke prognosis as well as whether insulin resistance is an independent prognostic factor. DESIGN: A non-randomized concurrent control experiment. SETTING: Department of Geriatric Disease, Second Affiliated Hospital of Kunming Medical College. PARTICIPANTS: A total of 106 inpatients with ischemic stroke of the cervical intal carotid artery, who had suffered from the disease within the previous 72 hours, were admitted to the Department of Neurology, First Affiliated Hospital of Kunming Medical College from March to December in 2005 and, recruited for the present study. All 106 inpatients corresponded to the diagnostic criteria of ischemic stroke, formulated at the Fourth National Cerebrovascular Disease Conference in 1995, and were confirmed as having had an ischemic stroke by CT/MRI examinations. The patient group consisted of 54 males and 52 females. An additional 50 healthy individuals, who received health examinations simultaneously, were included as controls. Among the control subjects, there were 26 males and 24 females. Informed consent for laboratory measurements was obtained from all subjects; this study was approved by the Hospital Ethics Committee.METHODS: Following admission, all subjects were inquired of age, gender, previous history, blood pressure, body temperature, admission time, and smoking habits. Meanwhile, they were scored on clinical neurological function deficits. At 24 hours after admission, blood glucose, total cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels were measured under the fasting condition. The control subjects were subjected to the same examinations and evaluation upon admission. In the two groups, insulin resistance degree was evaluated by the insulin sensitivity index (ISI). According to the ISI, patients were assigned into severe and mild insulin resistance subgroups. The insulin resistance degree and its correlations to stroke risk factors and stroke prognosis were analyzed separately by t-test, linear correlation analysis and logistic regression analysis.MAIN OUTCOME MEASURES: Comparisons of fasting blood glucose and insulin levels, ISI, blood pressure, and blood lipid level between the two groups; comparisons of neurological function deficit scores, daily living activity scores and complication incidence between the severe and mild insulin resistance patients at 4 weeks after onset. RESULTS: All 106 patients and 50 healthy subjects were included in the final analysis. On admission, in the patient group, the blood glucose and insulin levels were significantly higher, while the ISI was significantly lower, compared with the control group (t = 10.38-12.29, P < 0.05); At 4 weeks after admission, in the patient group, blood glucose level was decreased, but there was no significant difference compared with the control group (P > 0.05), insulin level was decreased, but it was significantly higher compared with the control group (t = 6.46, P < 0.05), and ISI was increased, but it was significantly lower compared with the control group (t = 66, P < 0.05). On admission and at 4 weeks after admission, ISI was negatively correlated with triglyceride level (r = -0.494, -0.459, P < 0.05) and positively correlated to high-density lipoprotein cholesterol level (r = 0.448, 0.310, P < 0.05); however, it was not correlated with total cholesterol or high-density lipoprotein cholesterol levels (P > 0.05). In the severe insulin resistance patients, clinical neurological function deficit scores and complication incidence were significantly higher, while daily living activity scores were significantly lower, compared with the mild insulin resistance patients (t = 5.352 9, 4.260 4, 0.070 6, P < 0.05). Logistic regression analysis demonstrated that ISI was finally excluded as an independent prognostic factor. CONCLUSION: Ischemic stroke patients presented with insulin resistance. Insulin resistance was correlated with conventional risk factors for stroke, including hypertension and lipid metabolism disorder. Insulin resistance was correlated with the prognosis of acute cerebral infarction patients, but it was not an independent predictive factor.