The relationship between glycaemic variability and cardiovascular complications in patients with acute myocardial infarction and type 2 diabetes: a report from the DIGAMI 2 trial

AIMS: Hyperglycaemia during hospitalization for acute myocardial infarction (AMI) is a risk predictor, but attempts to improve the prognosis by insulin-based glucose control have not been consistently successful. Increased glycaemic variability, a potential effect of insulin treatment, has been linked to a worse prognosis in critically ill patients. The present aim was to study the possibility of such a relation in patients with type 2 diabetes (T2DM) and AMI. METHOD AND RESULTS: We studied 578 T2DM patients who had glucose levels measured hourly while receiving an insulin-glucose infusion during the first 48 h of hospitalization for AMI. Three measures of glycaemic variability: root mean square error (RMSE), range, and slope were studied in relation to a composite endpoint of mortality, stroke, and reinfarction and to mortality. In unadjusted analyses, the mean level of glycaemic variability did not differ between patients who died during 12 months of follow-up compared with those who survived. In a Cox regression model adjusting for age and previous congestive heart failure, there was no increased risk for the composite endpoint associated with increased glycaemic variability; RMSE: hazard ratio (HR) 1.09 [95% confidence interval (CI) 0.93-1.27; P = 0.28], range: HR 1.01 (95% CI: 0.98-1.05; P = 0.47), and slope: HR 1.01 (95% CI: 0.99-1.04; P = 0.40). There was furthermore no increased risk in mortality; RMSE HR 1.14 (95% CI: 0.93-1.38; P = 0.21), range HR 1.03 (95% CI: 0.98-1.08; P = 0.28), and slope HR 1.01 (95% CI: 0.98-1.04; P = 0.55). CONCLUSION: The 1-year risk for death, reinfarction, or stroke did not relate to glycaemic variability in T2DM patients with AMI treated with insulin infusion.