Diabetes mellitus is a chronic metabolic disease that requires individual dietary therapy to control blood glucose levels. Diabetic patients tend to adhere to their dietary arrangements more actively after suffering medical complications due to untreated diabetes. Several individual characteristics have a possible relationship with the patient’s non-adherence to their diet. This study aimed to analyze the relationship between nutritional knowledge, formal education, and emotional intelligence with dietary adherence in type 2 diabetes mellitus (T2DM) patients. The research design used was cross-sectional. Data were collected through three questionnaires on nutritional knowledge, emotional intelligence, and dietary adherence in 100 T2DM outpatients at Dr. Soetomo General Hospital who were treated in 2021. The collected data was analyzed using bivariate analysis with the Rank Spearman test. This study shows that formal education was not significantly related (correlation coefficient r = 0.159, p-value = 0.114) to dietary adherence. Meanwhile, there was a moderately significant and positive linear relationship (r = 0.444, p = 0.000) between nutritional knowledge and dietary adherence. Similarly, to emotional intelligence, there was a moderately significant and positive linear relationship (r = 0.423, p = 0.000) between emotional intelligence and dietary adherence. To be concluded, there was no relationship between formal education and dietary adherence in T2DM patients. In contrast, nutritional knowledge and emotional intelligence have a moderately significant and positive linear relationship with the dietary adherence of T2DM patients.