Impaired glucose regulation, elevated glycated haemoglobin and cardiac ischaemic events in vascular surgery patients

AIMS: Cardiac morbidity and mortality is high in patients undergoing high-risk surgery. This study investigated whether impaired glucose regulation and elevated glycated haemoglobin (HbA(1c)) levels are associated with increased cardiac ischaemic events in vascular surgery patients. METHODS: Baseline glucose and HbA(1c) were measured in 401 vascular surgery patients. Glucose < 5.6 mmol/l was defined as normal. Fasting glucose 5.6-7.0 mmol/l or random glucose 5.6-11.1 mmol/l was defined as impaired glucose regulation. Fasting glucose > or = 7.0 or random glucose > or = 11.1 mmol/l was defined as diabetes. Perioperative ischaemia was identified by 72-h Holter monitoring. Troponin T was measured on days 1, 3 and 7 and before discharge. Cardiac death or Q-wave myocardial infarction was noted at 30-day and longer-term follow-up (mean 2.5 years). RESULTS: Mean (+/- sd) level for glucose was 6.3 +/- 2.3 mmol/l and for HbA(1c) 6.2 +/- 1.3%. Ischaemia, troponin release, 30-day and long-term cardiac events occurred in 27, 22, 6 and 17%, respectively. Using subjects with normal glucose levels as the reference category, multivariate analysis revealed that patients with impaired glucose regulation and diabetes were at 2.2- and 2.6-fold increased risk of ischaemia, 3.8- and 3.9-fold for troponin release, 4.3- and 4.8-fold for 30-day cardiac events and 1.9- and 3.1-fold for long-term cardiac events. Patients with HbA(1c) > 7.0% (n = 63, 16%) were at 2.8-fold, 2.1-fold, 5.3-fold and 5.6-fold increased risk for ischaemia, troponin release, 30-day and long-term cardiac events, respectively. CONCLUSIONS: Impaired glucose regulation and elevated HbA(1c) are risk factors for cardiac ischaemic events in vascular surgery patients.