BackgroundTriglyceride glucose (TyG) index is considered a reliable alternative marker of insulin resistance and an independent predictor of cardiovascular (CV) outcomes. However, the prognostic value of TyG index in patients with type 2 diabetes mellitus (T2DM) and acute myocardial infarction (AMI) remains unclear.MethodsA total of 1932 consecutive patients with T2DM and AMI were enrolled in this study. Patients were divided into tertiles according to their TyG index levels. The incidence of major adverse cardiac and cerebral events (MACCEs) was recorded. The TyG index was calculated as the ln [fasting triglycerides (mg/dL)xfasting plasma glucose (mg/dL)/2].ResultsCompeting risk regression revealed that the TyG index was positively associated with CV death [2.71(1.92 to 3.83), p<0.001], non-fatal MI [2.02(1.32 to 3.11), p=0.001], cardiac rehospitalization [2.42(1.81 to 3.24), p<0.001], revascularization [2.41(1.63 to 3.55), p<0.001] and composite MACCEs [2.32(1.92 to 2.80), p<0.001]. The area under ROC curve of the TyG index for predicting the occurrence of MACCEs was 0.604 [(0.578 to 0.630), p<0.001], with the cut-off value of 9.30. The addition of TyG index to a baseline risk model had an incremental effect on the predictive value for MACCEs [net reclassification improvement (NRI): 0.190 (0.094 to 0.337); integrated discrimination improvement (IDI): 0.027 (0.013 to 0.041); C-index: 0.685 (0.663 to 0.707), all p<0.001].ConclusionsThe TyG index was significantly associated with MACCEs, suggesting that the TyG index may be a valid marker for risk stratification and prognosis in patients with T2DM and AMI.Trial registration Retrospectively registered.