This review explores the impact of gender on medication adherence in the context of metabolic and cardiovascular diseases. Optimal adherence to medication is crucial for achieving treatment goals and preventing adverse outcomes in chronic diseases. The review examines specific conditions such as type 2 diabetes, hypercholesterolemia, arterial hypertension, cardiovascular diseases, and heart failure. In type 2 diabetes, female sex, younger age, new drug prescription, non-white ethnicity, low education level, and low income were identified as predictors of non-adherence. Depressive disorders were also found to influence adherence. In hypercholesterolemia, women exhibited poorer adherence to statin therapy compared to men, with statin-related side effects and patient perception being significant factors. Adherence to anti-hypertensive therapy showed conflicting results, with studies reporting both higher and lower adherence in women. Limited evidence suggests that women may have poorer adherence after acute myocardial infarction and stroke. Regarding heart failure, adherence studies have shown inconsistent findings. The reasons for gender differences in medication adherence are multifactorial and include sociodemographic, disease-related, treatment-related, and psychological factors. This review emphasizes the need for further research to better understand these differences and develop gender-customized interventions that can improve medication adherence and reduce the burden of metabolic and cardiovascular diseases.