Objectives: To study the prevalence of psychiatric disorders in adolescents with and without type 1 diabetes, the factors associated with its presence, and to test the reliability of a screening tool for use in clinical settings. Methods: Eighty-one adolescents were enrolled in this case-control study, including 36 diabetic participants and 45 controls. Clinical and sociodemographic data were collected and psychiatric symptoms and diagnoses were obtained from adolescents and their parents using a screening tool (Strengths & Difficulties Questionnaire) and a semi-structured interview (Development and Well-Being Assessment). Results: Psychiatric disorders were identified in 22.2% of the sample (30.56% among diabetic adolescents vs. 15.56% of controls: OR = 2.39, 95%CI 0.82-6.99; p = 0.11). Overweight (body mass index percentile ≥ 85) was the only factor associated with psychiatric disorder (OR = 3.07; 95%CI 1.03-9.14; p = 0.04). Compared to the semi-structured interview, the screening instrument showed 80% sensitivity, 96% specificity, 88.9% positive predictive value and 92.3% negative predictive value for the presence of psychiatric diagnoses in adolescents. Conclusion: Psychiatric morbidity was high in this sample of adolescents, especially among those with diabetes. Routine use of the Strengths and Difficulties Questionnaire can help with early detection of psychiatric disorders in this at-risk group.