Several studies have provided direct comparisons to widely accepted procedures such as LAGB and LRYGB (Table 1). Kehagias [8] randomized 60 patients with body mass index <50 (kg/m²) to LRYGB and LSG with 3 years follow-up. The results revealed a significantly better weight loss after sleeve in the first year. At 3 years, percent excess weight loss (% EWL) was 62 % after LRYGB and 68 % after LSG (P = 0.13), and both procedures were equally effective in the amelioration of comorbidities. Karamanakos et al. [9] performed a double-blind study comparing LSG and LRYGB that demonstrated better weight loss at 6 months (55.5 % ± 7.6 % vs. 50.2 % ± 6.5 %, p = 0.04) and at 12 months (69.7 % ± 14.6 % vs. 60.5 % ± 10.7 %, p = 0.05) in the LSG group. A randomized controlled trial by Himpens and colleagues [10] compared LAGB and LSG and found significantly better weight loss at 3 years after LSG (48 % vs. 66 % EWL, respectively).

Carlin et al. [11] reported data from the Michigan Bariatric Surgery Collaborative regarding the risks and benefits of LSG compared to LAGB and LRYGB. The study included 2,949 LSG patients and compared outcomes to 2,949 LAGB and 2,949 LRYGB patients who were matched for 23 baseline characteristics. Excess weight loss, complications, comorbidity remission, and QOL were assessed at 30 days, 1, 2, and 3 years postoperatively. The complication rates, weight loss, and comorbidity improvement for LSG were intermediate between LAGB and LRYGB in this large study (Figs. 2 and 3).

A comprehensive literature review of LSG shows a mean % EWL after LSG ranging from 47 to 83 % at 2 years and 66 % at 3 years. The reported overall mean % EWL after LSG was 55 % with average follow-up less than 3 years [6] and % EWL ranging from 48 to 69 % with follow-up more than 5 years (Table 2). Most of the earlier reports using LSG included high-risk patients with a planned second-stage gastric bypass or duodenal switch. Some of these patients had sufficient weight loss and those with reduction in comorbidities with the sleeve alone did not undergo the second-stage operation for personal or insurance reasons. Eid et al. [12] reported outcomes for 74 patients who did not undergo their planned second-stage operation. Long-term follow-up data was available for 69 patients (93 % follow-up). Mean patient age at the time of surgery was 50 years and the mean preoperative BMI was 66 ± 7 kg/m² (range, 43–90). Most patients had significant comorbid conditions a mean of nine (range, 2–17) per patient. The high-risk status of this patient population was demonstrated by the fact that 54 % were classified as ASA IV by the American Society of Anesthesiology, and the remaining 46 % were classified as ASA III status before surgery. The mean length of follow-up was 73 months (range, 38–95 months). Mean % EWL at 38–60 months, 61–72 months, 73–84 months, and 85–95 months was 51 %, 52 %, 43 %, and 46 %, respectively, with an overall % EWL of 48 % for the entire group. These patients provide evidence regarding the effectiveness and durability of LSG for severe obesity, even in high-risk patients.

Sarela et al. [13] reported 8–9-year follow-up data for LSG as a definitive bariatric procedure for 13 out of 20 patients. Of the remainder, 4 patients underwent revision surgery and 3 were lost to follow-up after 2 years. The small number of patients in that series did not permit statistically meaningful comparison at additional intervals. For the entire cohort, the median % EWL was 68 % (range, 18–85 %) at 8 or 9 years.

D’Hondt et al. [14] had 83 patients (81.4 %) who were eligible for long-term follow-up evaluation. Their mean initial body mass index (BMI) was 39.3 kg/m². No major complications occurred. At a median follow-up point of 49 months (range, 17–80 months), the mean % EWL was 72.3 % ± 29.3 %. For the 23 patients who reached the 6-year follow-up point, the mean % EWL was 55.9 % ± 25.55 %. The overall success rate (% EWL > 50 %) was 85.7 % after 4 years, 64.3 % after 5 years, and 54.5 % after 6 years. The % EWL reported by the surgeons in a survey at the Third International Summit for LSG 4 and 5 years was 57.3 % and 60.0 %, respectively [15].

Diabetes is currently a major public health problem in both developed and developing countries. Like obesity, type 2 diabetes mellitus (T2DM) is a chronic disease, with increasing prevalence. T2DM is challenging to control with current therapies that include diets, drug therapy, and behavioral modification, especially in obese patients. Bariatric surgery has become a powerful tool in the management of these closely related disease processes.

Schauer et al. [16] published a randomized controlled, single-center trial, evaluating the efficacy of intensive medical therapy (IMT) alone versus medical therapy plus LRYGB versus IMT plus LSG in 150 patients with a BMI of 27–43 and an uncontrolled type 2 diabetes. Ninety-one percent of patients completed 36 months of follow-up. The proportion of patients achieving the primary end point (glycated hemoglobin level of 6.0 % or less at 36 months) was 5 % in the medical-therapy group versus 38 % in the gastric-bypass group (P < 0.001) and 24 % in the sleeve-gastrectomy group (P = 0.01). The use of glucose-lowering medications, including insulin, was lower in the surgical groups than in the medical group. Patients in the surgical groups had greater total weight loss, with reductions of 24.5 ± 9.1 % in the gastric-bypass group and 21.1 ± 8.9 % in the sleeve-gastrectomy group, as compared with a reduction of 4.2 ± 8.3 % in the medical-therapy group (P < 0.001 for both comparisons).