A meta-analysis assessing the effect of orlistat on glycaemic control in overweight and obese patients with type 2 diabetes mellitus included 12 RCTs. The overall mean weight reduction (3, 6 and 12 months) in the orlistat group was -4.25 kg (95% CI -4.5 to -3.9 kg). The mean weight difference between treatment and control groups was -2.10 kg (95% CI -2.3 to -1.8 kg, P < 0.001), the mean HbA1c difference was -6.12 mmol /mol (95% CI -10.3 to -1.9, P < 0.004) and the mean fasting blood glucose difference was -1.16 mmol /L( 95% CI - 1.4 to -0.8 mmol /L, P < 0.001). Treatment with orlistat plus lifestyle intervention resulted in significantly greater weight loss and improved glycaemic control in overweight and obese patients with type 2 diabetes compared with lifestyle intervention alone.
A Cochrane review included 22 studies, with a total of 296 participants for fluoxetine, 2036 for orlistat, and 1047 for sibutramine. Pharmacotherapy produced modest reductions in weight for fluoxetine (5.1 kg (95% confidence interval [CI], 3.3–6.9) at 24 to 26 weeks follow up; orlistat 2.0 kg (CI, 1.3–2.8) at 12 to 57 weeks follow-up, and sibutramine 5.1 kg (CI, 3.2–7.0) at 12 to 52 weeks follow-up. Glycated hemoglobin also modestly and significantly reduced for fluoxetine and orlistat. Gastrointestinal side effects were common with orlistat; tremor, somnolence and sweating with fluoxetine; and palpitations with sibutramine.
Some studies, using a variety of study designs, were available on other drugs and a significant decrease in weight was noted in three studies of mazindol, one of phenmetrazine, two of phentermine. The reporting of these studies did not allow quantitative synthesis of results.