The influence of pre‐admission hypoglycaemic therapy on cardiac morbidity and mortality in type 2 diabetic patients undergoing major non‐cardiac surgery: a prospective observational study*

It remains unclear whether type 2 diabetics treated with either insulin or oral hypoglycaemic agents have the same incidence of cardiac morbidity and mortality after major non-cardiac surgery. We prospectively studied 360 type 2 diabetic patients undergoing major non-cardiac surgery of which 105 were treated with insulin only, 171 were treated with oral hypoglycaemics only and 84 were treated with a combination of insulin and oral hypoglycaemics. All-cause mortality after 30 days and after 12 months was highest in the insulin (10% and 26%) and lowest in the oral hypoglycaemics group (2% and 13%; p = 0.02 and 0.007, respectively). Insulin treatment was independently associated with increased mortality after 30 days (hazard ratio 3.93; 95% CI 1.22-12.64; p = 0.022) and 12 months (hazard ratio 2.03; 95% CI 1.16-3.58; p = 0.014) after multivariate adjustment for age, sex and the revised cardiac risk index (insulin treatment excluded). The increased mortality in insulin-treated diabetic patients may be due to a more progressive disease state in these patients rather than the treatment modality itself.