BACKGROUND: Prediabetes (pre-DM) is recognized as an intermediate state of glucose metabolism with a high potential to progress to diabetes mellitus (DM). However, its prognostic value in patients with premature acute myocardial infarction (PAMI) under the age of 35 remains unclear. This study aimed to investigate the relationship between pre-DM and long-term cardiovascular outcomes in this unique population. METHODS: This retrospective cohort study included 796 PAMI patients under 35 years of age who were categorized into three groups based to glycated hemoglobin levels or previous history: normal glucose regulation (NGR), pre-DM, and DM. The primary endpoint was the occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) including all-cause death, non-fatal myocardial infarction, non-fatal stroke, or revascularization. Multivariable Cox regression, Kaplan-Meier and Subgroup analyses were performed. RESULTS: Pre-DM was observed in 22.1% of the PAMI cohort. During the median follow-up of 81 months, the incidence of MACCE was 23.5%, with significantly higher rates in the pre-DM and DM group compared to the NGR group (18.4%, 27.3%, 34.2%
p <
0.001). After adjusting for confounding variables, pre-DM remained independently associated with an increased risk of MACCE (HR 1.51, 95%CI 1.05-2.18, p = 0.027). Subgroup analysis demonstrated that pre-DM status was a robust risk factor compared to NGR. Moreover, pre-DM had a similar impact on MACCE events as DM in patients with PAMI. CONCLUSIONS: Pre-DM is associated with a poor prognosis in young AMI patients under 35 years old, suggesting that it may be an independent predictor of adverse events in this population.