A better metabolic control is an important objective of health care in diabetes mellitus. This objective has been achieved elsewhere, incorporating group visits to the usual care of diabetic patients. To evaluate the effects of a primary care group visit model after 9 and 15 months of implementation, on the metabolic control of diabetic patients. Two cohorts of type 2 diabetic patients, matched by sex, age and fasting plasma glucose (FPG) were studied. Group visits (monthly medical consultation and one hour sessions with group interaction on the same day) were implemented in 600 patients and routine visits (monthly one-to-one medical consultation) were implemented in 601 patients. The evolution on FPG, cholesterol, systolic (SBP) and diastolic blood pressure (DBF) and body mass index (BMI) were compared. At 15 months of follow up, mean FPG was lower in patients with group visits compared to those in usual individual care (155.3 +/- 59.5 and 175.7 +/- 67.7 mg/dL respectively, p