Prevalence and prediction of unrecognised diabetes mellitus and impaired glucose tolerance following acute stroke

Background: diabetes mellitus not only increases the risk of ischaemic stroke two- to four-fold but also adversely influences prognosis. The prevalence of recognised diabetes mellitus in acute stroke patients is between 8 and 20%, but between 6 and 42% of patients may have undiagnosed diabetes mellitus before presentation. Post-stroke hyperglycaemia is frequent and of limited diagnostic value and the oral glucose tolerance test assumes that the patient is clinically stable and eating normally. There is a need for a simple and reliable method to predict new diabetes mellitus in acute stroke patients. Objectives: to determine the prevalence of unrecognised diabetes mellitus and impaired glucose tolerance on hospital admission and 12 weeks later in acute stroke patients with post-stroke hyperglycaemiagreater than or equal to6.1 mmol/l. To measure the accuracy of hyperglycaemia and elevated glycosylated haemoglobin concentration in predicting the presence of unrecognised diabetes mellitus at 12 weeks. Design: acute (<24 hours) stroke patients (cerebral infarction and primary intracerebral haemorrhage) with admission hyperglycaemia between 6.0 and 17 mmol/l and without a previous history of insulin-treated diabetes mellitus who were randomised into the Glucose Insulin in Stroke Trial between October 1997 and May 1999 were studied. The Glucose Insulin in Stroke Trial is a randomised controlled trial investigating the benefits of maintaining euglycaemia in acute stroke patients with mild to moderate hyperglycaemia. At 12 weeks, survivors underwent a 75 g oral glucose tolerance test. The positive predictive value and negative predictive value of admission plasma glucose >= 6.1 mmol/l and elevated glycosylated haemoglobin concentration in predicting the presence of diabetes mellitus were used to estimate the prevalence of unrecognised diabetes mellitus in a consecutive series of 582 acute stroke admissions. Results: 582 consecutive acute stroke patients were assessed for eligibility for the Glucose Insulin Stroke Trial, of whom 83 (14%) had recognised diabetes mellitus. One hundred and forty-two patients were randomised and 62 underwent a 3-month oral glucose tolerance test, of whom 26 (42%) had normal glucose tolerance, 23 (37%) had impaired glucose tolerance and 13 (21%) had diabetes mellitus. Admission plasma glucose >= 6.1 mmol/l and glycosylated haemoglobin >= 6.2% predicted the presence of previously unrecognised diabetes mellitus at 12 weeks with a positive predictive value of 80% and negative predictive value of 96%. The estimated prevalence of unrecognised diabetes mellitus in the total series of acute stroke admissions was 16-24%. Conclusions: one-third of all acute stroke patients may have diabetes mellitus. For patients presenting with post-stroke hyperglycaemia, impaired glucose tolerance or diabetes mellitus is present in two-thirds of survivors at 12 weeks. Admission plasma glucose >= 6.1 mmol/l combined with glycosylated haemoglobin >= 6.2% are good predictors of the presence of diabetes mellitus following stroke.