Gastric bypass (GBP) has proved its efficacy 30 years ago in the management of diabetes mellitus (T2DM) for severe obese patients. More recently, interesting results have been published after sleeve gastrectomy (SG) in the same indication. Between 2005 and 2008, three bariatric centers have prospectively collected the data of T2DM patients treated by laparoscopic gastric bypass (LGBP) or laparoscopic sleeve gastrectomy (LSG). Effects on hemoglobin A1c (HbA1c), pharmacological treatment and excess weight loss after 1 year of surgery have been analyzed. All patients (35 LGBP and 33 LSG) were treated with oral anti-diabetics (OAD) or insulin before surgery (32 OAD and three insulin in LGBP group and 27 OAD and six insulin in LSG group). The average body mass index (BMI) in the LGBP group was 47.9 and 50.6 kg/m² in the LSG group. At 1 year after surgery, the average HbA1c lost was 2,537 in the GBP group and 2,175 in the SG group. T2DM had resolved (withdrawal of pharmacological treatment) in 60% of the LGBP group and 75.8% of the LSG group. Reduced use of pharmacological therapy was noted in 31.42% of the LGBP group and 15.15% of the LSG group. Percentage excess weight loss and BMI lost were 56.35% and 29.75% in the LGBP group and 60.11% and 29.80% in the LSG group, respectively. During short-term follow-up, the impact on regulation of HbA1c blood level of LGBP or LSG is important. At 1 year after surgery, LSG seems to be as effective as LGBP for the management of T2DM in severely obese patients.