Abstract: Objective To investigate the predictive value of glycemic gap for in-hospital mortality in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI). Methods A total of 566 STEMI patients who underwent pPCI at the People's Hospital of Suining County from December 10,2018, to November 10,2022 were selected and their clinical data were collected for retrospective analysis. According to the presence of in-hospital mortality, the patients were divided into a mortality group (n=26) and a survival group(n=540). Cox proportional hazards regression was used to analyze the risk factors for in-hospital mortality in STEMI patients. Results Among the 566 STEMI patients included in the study, 26 (4.59%) died during hospitalization. Multivariate Cox regression analysis showed that glycemic gap, age, Killip classification, door-to-wire (D2W) time, and peak C-reactive protein (CRP) levels were independent risk factors for in-hospital mortality in STEMI patients. The receiver operating characteristic (ROC) curve indicated that the area under the curve (AUC) for glycemic gap in predicting in-hospital mortality in STEMI patients was 0.724 (95% CI: 0.617-0.832, P<0.001). Kaplan-Meier survival analysis revealed that STEMI patients with higher glycemic gap levels had a significantly increased risk of in-hospital mortality (P<0.05). Conclusions Glycemic gap is an independent predictor of in-hospital mortality in STEMI patients undergoing pPCI. It can serve as a simple and effective marker for risk stratification in this patient population.