People with diabetes or prediabetes face a higher risk of cardiovascular events. However, the impact of sex and menopausal hormone therapy on cardiovascular disease (CVD) in these individuals remains unclear. We examined cardiovascular event risk and the association between menopausal hormone therapy and CVD risk in female Koreans with diabetes or prediabetes. We utilized the National Health Insurance Service database from 2009 to 2019. People undergoing hemodialysis or with an eGFR < 15 mL/min/1.73 m were excluded. We analyzed 1,313,591 people with prediabetes and 890,184 people with diabetes without a history of heart failure. Additionally, we examined 1,180,576 people with prediabetes and 673,688 people with diabetes without a history of acute myocardial infarction or stroke. Hazard ratios (HRs) for CVD risk were calculated using Cox proportional hazards models. Women with diabetes had a higher risk of heart failure compared to men with diabetes (HR: 1.095, 95% CI 1.068 to 1.123), a pattern also seen in people with prediabetes (HR: 1.150, 95% CI 1.118 to 1.183). Conversely, women with diabetes had a lower risk of acute myocardial infarction (HR: 0.507, 95% CI 0.486 to 0.528) and stroke (HR: 0.787, 95% CI 0.771 to 0.804) compared to men with diabetes, which was similarly observed in people with prediabetes. Hormone therapy was linked to a reduced risk of ischemic stroke in postmenopausal women with diabetes (HR: 0.761, 95% CI 0.589 to 0.983) and prediabetes (HR: 0.659, 95% CI 0.488 to 0.889). Women with diabetes or prediabetes have a higher risk of heart failure than men. More intensive screening and management of heart failure are needed, especially for these women. Conversely, women with diabetes or prediabetes have a lower risk of acute myocardial infarction and stroke compared to men. Menopausal hormone therapy may help prevent ischemic stroke in postmenopausal women with diabetes or prediabetes.