Metabolic results of bariatric surgery have determined an expansion of its traditional indications, being increasingly performed in non-severely obese patients, especially in type 2 diabetes mellitus (T2DM). Our aim is to determine the effectiveness of laparoscopic Roux-en-Y gastric bypass (LRYGB) in T2DM remission in patients with body mass index (BMI) below 35 kg/m(2) and the variables associated with T2DM remission after surgery. Retrospective analysis of diabetic patients with BMI < 35 kg/m(2) who underwent LRYGB in our center between 2002 and 2010 was done. We analyzed patient's demographics, comorbidities, BMI, excess weight loss percentage (EWLp), complications, and metabolic results at 3 years. Univariate and multivariate analyses were performed to determine variables associated with T2DM remission. One hundred patients were included. Sixty patients (60 %) were women; median age was 48 years old (interquartile range (IQR) 42-54), and median preoperative BMI was 32.7 kg/m(2) (IQR 31.6-34.1). Median preoperative duration of T2DM was 4 years (IQR 2-7), with 49, 30, 2, and 18 % on treatment with one, two, and three hypoglycemic agents and insulin, respectively. Ninety-four percent achieved 36-month follow-up, and at this time, median EWLp was 93 % (IQR 67-121). A total of 53.2, 9.6, 25.5, and 11.7 % achieved a T2DM complete remission, partial remission, improvement, and no improvement, respectively. T2DM remission only was associated with non-insulin use in multivariate analysis, with an OR = 15.1 (2.8-81.2) and p = 0.002. LRYGB is a reliable and effective treatment in diabetic patients with a BMI < 35 kg/m(2) at 3 years. T2DM remission's best results are observed in non-insulin diabetic patients.