Influence of diabetes mellitus on operative risk.

In a retrospective study postoperative morbidity was compared between 224 patients with diabetes mellitus and 224 non-diabetic control patients matched with regard to operative procedure (major vascular, abdominal and acute surgery for hip fracture), sex, age, complicating cardiovascular disease and weight. Forty-six patients in each group had complications, without any trend towards specific morbidity in the diabetic group. Incidence of morbidity was similar in diabetic patients treated with insulin, oral antidiabetic agents or diet. Diabetic patients with complications had significantly (P less than 0.01) lower blood glucose pre- and postoperatively than those without complications. The risk of overlooking (type II error) a 25 per cent increase in complication rate in the diabetic patients was less than 10 per cent and the risk of overlooking a 50 per cent increase in morbidity less than 0.5 per cent. These results do not support the common belief that diabetes per se may increase surgical risk.