Twenty-seven studies (n=673 participants) were included: three prospective non-randomised controlled trials, three retrospective controlled studies, 15 prospective case series and six retrospective case series. Mean follow-up was 13.1 months (range three to 36 months).
The mean rate of type 2 diabetes resolution was 66.2% (range 14% to 100%). In 16 studies that reported resolution and improvement, 97.1% of participants experienced one outcome or the other.
Mean excess weight loss was 47.3% (range 6.3% to 74.5%; 11 studies). Mean BMI decreased from 47.4kg/m2 at baseline to 35.9kg/m2 at follow-up (range 24.6 to 44.7; eight studies). Plasma glucose levels decreased from a mean of 181.2mg/dL to 119.2mg/dL (range 96.7 to 157.2; seven studies). HbA1c levels decreased by 1.7% at follow-up (range 0.5% to 3%; 11 studies).
Adverse events data were derived from 1,117 patients who underwent laparoscopic sleeve gastrectomy (not all patients had diabetes mellitus). Operative mortality in the first 30 days was 0.36%, postoperative complications such as bleeding occurred in 1.79% of patients, postoperative abscess or infection occurred in 0.27% of patients and postoperative leaks occurred in 1.97% of patients.