Orlistat 120 mg improves glycaemic control in type 2 diabetic patients with or without concurrent weight loss

Background: Both obesity and type 2 diabetes are associated with increased morbidity and mortality. Published data suggest that orlistat 120 mg, a lipase inhibitor used to treat obesity, may improve glycaemic parameters through weight loss–independent effects. Aim: To investigate the effect of orlistat 120 mg on weight loss, and assess whether changes in glycaemic parameters fasting plasma glucose (FPG) and haemoglobin A_1c (HbA_1c)] are independent of weight loss. Methods: This retrospective analysis of pooled data from seven multicentre, double‐blind, placebo‐controlled studies involved overweight or obese patients with type 2 diabetes (aged 18–70 years). Patients were required to have a body mass index of 27–43 kg/m², HbA_1c of 6.5 to <13%, and stable weight for ≥3 months. Subjects received orlistat 120 mg tid or placebo for 6 or 12 months. Results: A total of 2550 overweight or obese patients with type 2 diabetes were enrolled and randomized to treatment with orlistat 120 mg tid (n = 1279) or placebo (n = 1271). For the whole population, patients treated with orlistat 120 mg had significantly greater mean decreases in FPG compared with placebo‐treated patients (?1.39 mmol/l vs. ?0.47 mmol/l; p < 0.0001). In addition, orlistat 120 mg provided significantly larger mean decreases in HbA_1c compared with placebo (?0.74% vs. ?0.31%; p < 0.0001). For patients with minimal weight loss (≤1% of baseline body weight), orlistat 120 mg still provided a significantly greater decrease in the least squares mean value for both FPG (?0.83 mmol/l vs. ±0.02 mmol/l; p = 0.0052) and HbA_1c?0.29% vs. ±0.14%; p = 0.0008). This suggested that the improvement of glycaemic control with orlistat 120 mg was independent of weight loss. Using linear regression analysis, improvement in glycaemic control (FPG and HbA_1c) with orlistat 120 mg was less strongly correlated with weight loss than for placebo. Conclusion: Orlistat 120 mg appears to improve glycaemic control more than would be predicted by weight loss alone in overweight or obese patients with type 2 diabetes. Postulated mechanisms underlying this effect include an improvement of insulin sensitivity, a slower and incomplete digestion of dietary fat, reduction of postprandial plasma non‐esterified fatty acids, decreased visceral adipose tissue, and stimulation of glucagon‐like peptide‐1 secretion in the lower small intestine.