OBJECTIVE: Patients with diabetes are considered to be at high surgical risk due to the potential occurrence of cardiovascular and diabetes-related complications. Limited research exists on the cardiovascular risk profiles of patients with prediabetes and undiagnosed diabetes in noncardiac surgery. In this population-based cohort study, we investigated different glycated hemoglobin levels and their associated postoperative cardiovascular risks. METHODS: In this perioperative cohort study, participants were categorized into four groups: nondiabetes, prediabetes, undiagnosed diabetes, and diagnosed diabetes. The primary endpoint was the occurrence of major adverse cardiovascular events (MACE) at 30 days postoperatively, with secondary outcomes assessed at 90 days. The association between various groups and postoperative MACE was evaluated using Cox proportional hazards models and Kaplan-Meier curves. Subgroup analyses and sensitivity analyses were also performed. RESULTS: We enrolled 13 207 eligible patients undergoing noncardiac surgeries, among whom 3841 (29.08%) had prediabetes and 1521 (11.52%) had undiagnosed diabetes. In the 30-day postoperative period, the prediabetes group (hazard ratio [HR] [95% CI]: 1.70 [1.15, 2.52]), undiagnosed diabetes group (HR [95% CI]: 2.36 [1.15, 3.68]), and diagnosed diabetes group (HR [95% CI]: 2.33 [1.54, 3.53]) exhibited increased risks of MACE compared to the nondiabetes group. Similar findings were observed for the 90-day postoperative MACE. Further subgroup analysis revealed a significant interaction between sex and states of glycemic regulation (P for interaction <
0.005). CONCLUSION: In this cohort, a notable proportion of patients with prediabetes or undiagnosed diabetes were found to be undergoing noncardiac surgeries. They were associated with an increased risk of developing postoperative MACE.