Orlistat is a nonsystemically acting gastric and pancreatic lipase inhibitor that limits the absorption of dietary fat. A retrospective pooled analysis of three 2-year, double-blind, randomised, placebo-controlled trials involving patients with obesity revealed that orlistat recipients were more likely to experience an improvement, and less likely to experience a deterioration, in glucose tolerance status than placebo recipients. In comparison with placebo, orlistat recipients had significantly greater reductions in glycosylated haemoglobin and fasting plasma glucose levels in large, double-blind, randomised, placebo-controlled studies of 24 to 52 weeks' duration involving patients with obesity and type 2 diabetes mellitus. In one such study, the dosage of concomitant sulphonylureas was able to be reduced in more orlistat than placebo recipients (43.2 vs 28.9%), with discontinuation of sulphonylurea therapy achieved in 11.7% of orlistat recipients. The most common adverse effects reported in orlistat recipients with type 2 diabetes mellitus relate to the gastrointestinal system and are similar to those reported in studies involving patients without type 2 diabetes mellitus.
