Objective: To evaluate clinical and laboratory profiles of patients with type 1 diabetes mellitus in three public hospitals in São Paulo, Brazil, since type 1 diabetes mellitus is a chronic illness that occurs mainly in the pediatric age group in the Brazilian population. Methods: Cross-sectional study with patients followed up in reference centers in São José do Rio Preto (FAMERP), Campinas (UNICAMP) and São Paulo (Conjunto Hospitalar do Mandaqui). Data about gender, age, diabetes duration, daily insulin dose, number of daily insulin injections, and glycosylated hemoglobin (HbA1c) were analyzed. Results: Two hundred and thirty-nine patients (131 females) were evaluated; mean age was 13.1±4.7 years and mean diabetes duration was 6.6±4.2 years. Daily insulin doses ranged from 0.1 to 1.78 units/kg/day (0.88±0.28), and 180 (74.7%) patients had two daily injections. HbA 1c ranged from 4.6 to 17.9% (10.0±2.3%). 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