The effects of pharmacologic agents for type 2 diabetes mellitus on body weight. 
Type 2 diabetes mellitus and obesity share a pathogenic relationship, and both have rapidly increased in prevalence over the past decade.  This review evaluates the effects of antidiabetes therapies on weight and glycemic control in the type 2 diabetes mellitus population.  A PubMed search was conducted to identify randomized controlled trials that reported the weight effects of antidiabetes treatments.  The search focused on the newer incretin-based therapies, including dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) agonists.  Antiobesity drugs and treatment options potentially available to patients with type 2 diabetes mellitus, including bariatric surgery, were also examined.  Most of the established antidiabetes therapies (eg, sulfonylureas, thiazolidinediones) promote weight gain, thereby exacerbating insulin resistance and glucose intolerance.  Dipeptidyl peptidase-4 inhibitors exhibit a weight-neutral profile, however, and GLP-1 receptor agonists (eg, exenatide, liraglutide) have achieved significant body weight reductions in spite of improved glycemic control, which is often accompanied by weight gain.  Antiobesity drugs, such as orlistat and sibutramine, are effective weight-lowering agents in patients with type 2 diabetes mellitus, but safety and tolerability concerns may limit their use.  Bariatric surgery in obese patients is associated with improved glycemic values and decreased mortality.  Clinical evidence substantiating the weight-neutral effects of DPP-4 inhibitors and the weight-loss effects of GLP-1 agonists is promising, offering an expansion of therapeutic options for overweight and obese patients with type 2 diabetes mellitus.  Evidence on the clinical utility of antiobesity drugs is more equivocal, and more data are needed to evaluate the safety and tolerability of these agents.