The aim of this study is to examine the relationship between fatalistic beliefs, self-care, and glycemic control among Mexican men with type 2 diabetes mellitus. This is a cross-sectional study in men diagnosed with type 2 diabetes mellitus from 18 to 59 years of age from the Northeast of Mexico. Fatalistic beliefs, self-care, medication adherence, and HbA1C were evaluated. Patients were divided into glycemic control (<7% HbA1c) and without glycemic control (>7% HbA1c). Tests were performed to compare 2 independent groups, Student’s t and U Mann Whitney. Correlation tests and multiple linear regression models were also performed. For statistical analysis, the SPSS v27 program was used. Forty-nine percent of the men had glycemic control (<7% HbA1c). Fatalistic beliefs were negatively correlated with self-care and medication adherence, but not with HbA1c. In multiple linear regression models, fatalistic beliefs were a negative predictor of self-care and medication adherence. In the model for HbA1c, the pessimism subdimension and self-care were the predictors. Fatalistic beliefs negatively affect self-care compliance and medication adherence, while the pessimism subdimension was related to the increase in HbA1c.