Type 2 diabetes mellitus (T2DM) is a chronic disease that affects a person's general well-being. Current evidence sets an association between psychological well-being and controlled metabolic parameters. People newly diagnosed with T2DM show higher prevalence of depression and anxiety symptoms. Cognitive behavioral therapy (CBT) has effectively improved psychological adjustment, but most studies do not specifically address recently diagnosed people nor usually include long-term follow-up measures. Objective We sought to assess changes in psychological variables in people with newly diagnosed diabetes who received a cognitive–behavioral intervention, within a comprehensive care program. Method 1208 adults with T2DM (≤5 years) who attended a national health institute in Mexico received a cognitive–behavioral intervention aimed at improving quality of life and reducing emotional distress that often interferes with diabetes control, as well as evaluating cognitive and emotional resources and social support. Measures of quality of life, diabetes-related distress, anxiety and depression questionnaires were compared at pre-test, post-test and follow up using Friedman's ANOVAs. Multiple logistic regression models evaluated glycosylated hemoglobin (HbA1c) and triglycerides control at post-test and follow up. Results Questionnaire measures and metabolic variables significantly decreased symptomatology at post-test and these changes maintained at follow-up. Significant associations were found between quality-of-life scores and HbA1c and triglycerides levels in post-test and follow-up. Diabetes-related distress scores increased the odds of having adequate HbA1c control at post-test. Conclusion This study contributes to the evidence on the importance of considering psychological factors as part of comprehensive diabetes care to improve quality of life and emotional burden and facilitate the achievement of metabolic goals.