Antidiabetic agents and weight
While some antidiabetic agents are weight-neutral and others promote weight loss, several therapies are associated with weight gain6 (TABLE 13). Patients like Mr. P can gain as much as 10 kg in 3 to 6 months after beginning treatment with insulin, thiazolidinediones (TZDs), sulfonylureas, and other insulin secretagogues.2,7
A recent systematic review and meta-analysis of 257 randomized controlled trials (RCTs) found weight gain to be associated with the use of pioglitazone (2.6 kg), glimepiride (2.1 kg), glyburide (2.6 kg), glipizide (2.2 kg), and sitagliptin (0.55 kg). A modest weight loss was associated with acarbose, exenatide, liraglutide, metformin, miglitol, and pramlintide.8
Sulfonylureas are generally associated with a 1.5 to 2.5 kg weight gain.9-11 In an analysis of 27 RCTs of noninsulin antidiabetic drugs in patients whose disease was not controlled by metformin alone, TZDs, sulfonylureas, and meglitinides were associated with a 1.77 to 2.08 kg weight gain.9 Furthermore, those taking sulfonylureas and meglitinides had higher rates of hypoglycemia compared with patients taking placebo (relative risk, 4.50-7.50). In fact, sulfonylureas have the highest risk of serious hypoglycemia of any noninsulin therapy.6
In contrast, metformin—the most commonly prescribed oral agent for type 2 diabetes—promotes mild weight loss by multiple mechanisms and has a good safety profile.12,13 Thus, some physicians use metformin off label for weight loss and diabetes prevention and have suggested that it be approved for these indications.13
Glycemic control and weight loss
Glucagon-like peptide-1 (GLP-1) agonists lead to weight loss by decreasing appetite and enhancing satiety, as well as improving glycemic control. Liraglutide received Food and Drug Administration (FDA) approval in 2014 as a treatment for chronic weight management at a higher dose (3 mg/d) than that used to treat diabetes (1.8 mg/d).14
Sodium-glucose co-transporter 2 (SGLT2) inhibitors are a relatively new class of antidiabetic medication that reduce glucose reabsorption by the kidneys, leading to increased urinary glucose excretion.15 The associated weight loss, in addition to a reduction in hyperglycemia, may be due to the subsequent calorie loss through glycosuria.
Both dipeptidyl peptidase-4 (DPP-4) inhibitors and alpha-glucosidase inhibitors (AGIs) appear to be weight-neutral or to induce minimal changes in weight.16 Although the systematic review mentioned earlier found a 0.55 kg weight gain associated with sitagliptin,8 most studies of DPP-4 inhibitors report weight neutrality.17-19 Pramlintide, the amylin analogue that has FDA approval for use in combination with existing insulin treatment, can prevent weight gain or lead to weight loss.20,21
The Endocrine Society Clinical Practice Guideline recommends concomitantly prescribing at least one weight loss-promoting medication (such as metformin, a GLP-1 agonist, or pramlintide) to patients with obesity and type 2 diabetes who require insulin to mitigate weight gain due to insulin.2