Objective: To determine the importance of family support in the control of glucemia in non-insulin-dependent diabetes mellitus patients. Material and methods: A case and control study was designed where cases were patients with glycemia < 140 mg/dl and controls, patients with glycemia > or = 140 mg/dl. Family support was determined using the questionnaire Environmental Barriers to Adherence Scales which estimates the support lent by the family to the patient to follow therapeutic indications. The study consisted of 32 cases and 50 controls. Results: Family support received by the patient is significantly associated to the presence of glycemia < 140 mg/dl (OR = 3.9; 95% C.I. 1.4-11.1). Other variables did not show significant association. Conclusions: Family support lent to patients influences the control of glycemia.