Diabetes mellitus is one of the most prevalent diseases worldwide and is among the leading causes of loss of healthy years of life, which is aggravated in Brazil by accelerated population aging. This study aims to measure the problem of diabetes mellitus and its complications and characterize healthcare for diabetics in Brazil, according to regions. Prevalence rates were estimated using a multinomial regression model, and characterization of healthcare was based on triangulation between the Brazilian National Health Survey (PNS), the National Program for Improving Access and Quality in Primary Care (PMAQ-AB), and data from the Popular Pharmacy program. Diabetes prevalence in Brazil was 9.2%, according to the multinomial model, and prevalence in the corrected PNS (self-report + altered glycated hemoglobin - HbA1c > /= 6.5) was 9.4%. The proportion of diabetes mellitus underreporting in the country was 42.5%, reaching 72.8% in the North. Among individuals diagnosed with diabetes mellitus, half presented HbA1c > /= 6.5. Insufficient fundus eye examination (only 40% on average), with major regional variation (North 25% - Southeast 52%), is reflected in the high prevalence of retinopathy. Insufficient examination of feet (only 30%), can lead to more amputations. About 80% of diabetics used medications, indicating a persistently high proportion still without treatment. Healthcare deficiencies for diabetics lead to greater morbidity, hospitalizations (15%), and visits to emergency departments (27%, PMAQ). The scenario in 2012, although not ideal, occurred in a context of strengthening of the Brazilian Unified National Health System (SUS). The growing prevalence of diabetes mellitus and cutbacks in public health budgeting call for serious reflection on control of the disease in the coming years.