Insulin-sensitizing antihyperglycaemic medications are associated with better outcome in patients with diabetes undergoing cardiac stress testing

Background: There are several treatment modalities available for diabetes; however, the effects of the different medications on coronary artery disease are less understood. The purpose of this study was to evaluate the correlation of insulin-sensitizing therapy with the outcome of stress myocardial perfusion testing and to compare it with conventional therapy. Methods: Of 417 patients referred to stress testing for evaluation of chest pain, 222 were identified as being treated with conventional therapy only (insulin and insulin secretagogues) and 195 as being treated with insulin sensitizers (metformin and thiazolidinediones (TZD)). Multivariate logistic regression models were used to correct for confounding factors and to determine the independent relation between treatment type and stress-test outcome. Results: Ischaemia, infarction and the composite outcome were less frequent in the insulin-sensitizer group than in the conventional therapy group (odds ratio (OR) = 0.39, P = 0.025; OR = 0.32, P = 0.021 and OR = 0.38, P = 0.009, respectively). The subgroup analysis showed that treatment with metformin (n = 125) compared with conventional therapy was associated with less infarction or the composite outcome of ischaemia and/or ischaemia (OR = 0.18 (95% confidence interval (CI): 0.05-0.66), P = 0.010; OR = 0.34 (95%CI: 0.15-0.80), P = 0.014, respectively). Treatment with TZD (n = 43) was associated with a trend to less frequent ischaemia (OR = 0.18 (95%CI: 0.03-1.01), P = 0.051). Conclusion: The addition of insulin-sensitizing medications to the conventional diabetes therapy or their sole use was associated with decreased coronary artery disease or its severity in patients with diabetes as determined by stress myocardial perfusion study. Randomized prospective trials will be necessary to prove this benefit.