IMPORTANCE: Sulfonylureas are commonly used to treat type 2 diabetes (T2D). Research findings on cardiovascular risk associated with sulfonylureas have been inconsistent. OBJECTIVE: To emulate a target trial that compares the risk of cardiovascular events after initiation of treatment with individual sulfonylureas or dipeptidyl peptidase 4 inhibitors (DPP4is). DESIGN, SETTING, AND PARTICIPANTS: This comparative effectiveness research study included individuals with T2D and moderate cardiovascular risk treated with metformin monotherapy who received care at 1 of 10 US health systems or were insured by 1 of 2 large health insurance plans between January 1, 2014, and January 1, 2023. Data were analyzed from July 2024 to March 2025. EXPOSURE: Initiation of treatment with a sulfonylurea (glimepiride, glipizide, or glyburide) or a DPP4i (reference category) as a second line therapy after metformin. MAIN OUTCOMES AND MEASUREMENTS: The primary outcome was a 4-point composite of major adverse cardiovascular events (MACE-4): myocardial infarction, ischemic stroke, heart failure hospitalization, or cardiovascular death (from any of these conditions). The 5-year risks of each outcome were estimated. RESULTS: Among 48 165 eligible individuals (median [IQR] age, 61 [52-69] years; 22 674 female [47.1%]; median [IQR] hemoglobin A1C, 7.8% [7.3%-8.5%]; median [IQR] low-density lipoprotein cholesterol, 89 mg/dL [70-112 mg/dL]), 18 147 started glipizide, 14 282 started glimepiride, 1887 started glyburide, and 13 849 started a DPP4i. Over the median (IQR) follow-up of 37 (20-64) months, 3158 individuals (6.6%) experienced a MACE-4. The estimated 5-year risks of MACE-4 were 8.1% (95% CI, 7.5%-8.7%) for DPP4i, 8.4% (95% CI, 6.8%-9.9%) for glyburide, 8.6% (95% CI, 7.9%-9.2%) for glimepiride, and 9.1% (95% CI, 8.7%-9.7%) for glipizide. Compared with DPP4is, the 5-year risk ratio of MACE-4 was 1.13 (95% CI, 1.03-1.23) for glipizide, 1.07 (95% CI, 0.96-1.16) for glimepiride, and 1.04 (95% CI, 0.83-1.24) for glyburide. CONCLUSIONS AND RELEVANCE: In this comparative effectiveness research study of sulfonylureas vs DPP4i in patients with T2D, the risk of MACE-4 events was highest for glipizide. These findings suggest that sulfonylureas, glipizide in particular, may not be the optimal agent in treatment of individuals with T2D at moderate cardiovascular risk.