Comparison of survival after successful percutaneous coronary intervention of patients with diabetes mellitus receiving insulin versus those receiving only diet and/or oral hypoglycemic agents

The influence of diabetic treatment status on long-term outcome after percutaneous coronary intervention (PCI) is unclear. Previous reports have suggested that patients who receive insulin treatment have worse long-term outcome compared with patients who do not need insulin. To determine the influence of diabetes treatment status on outcome after PCI, patients with diabetes mellitus who underwent successful PCI from January 1, 1996, to June 30, 2001, were divided into 2 groups based on whether or not they required insulin; patients with shock or recent (≤7 days) myocardial infarction were excluded. Cox proportional hazards models were utilized to estimate the association between diabetes treatment status and long-term survival. One thousand one hundred four eligible diabetic patients were identified and divided into those treated with insulin (418 patients; median follow-up 35.5 months) and those treated with either an oral agent or diet alone (686 patients; median follow-up 27.9 months). Insulin-treated patients were less likely to be men, and had more previous coronary revascularizations, prior myocardial infarctions, and congestive heart failure on presentation. Angiographic and procedural characteristics were comparable. Unadjusted survival curves were constructed, demonstrating that insulin treatment was associated with worse survival than noninsulin treatment (p = 0.001). After adjusting for differences in baseline characteristics, insulin treatment did not adversely effect survival (odds ratio 1.10, 95% confidence intervals 0.77 to 1.58). Thus, among diabetic patients who underwent successful PCI, patients treated with insulin had worse survival. After adjusting for differences in baseline characteristics, insulin treatment was not independently associated with worse survival.