View the Table: GLP-1 and GIP/GLP-1 Receptor Agonists for Type 2 Diabetes

Glucagon-like peptide-1 (GLP-1) receptor agonists and the dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonist tirzepatide (Mounjaro) are widely prescribed for treatment of type 2 diabetes and weight management (see Table 1), but they delay gastric emptying and commonly cause nausea and vomiting. Gastroparesis and bowel obstruction (ileus) have also been reported with their use.

Diet, exercise, and weight loss can improve glycemic control, but almost all patients with type 2 diabetes require antihyperglycemic drug therapy. Treating to a target A1C of <7% while minimizing hypoglycemia is recommended to prevent microvascular complications of diabetes (retinopathy, nephropathy, and neuropathy). An A1C target of <8% may be appropriate for some older patients.

The FDA has approved tirzepatide (Mounjaro – Lilly), a peptide hormone with activity at both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors, to improve glycemic control in adults with type 2 diabetes. Tirzepatide, which is injected subcutaneously once weekly, is the first dual GIP/GLP-1 receptor agonist to become available in the US. Selective GIP receptor agonists are not available in the US; GLP-1 receptor agonists have been available for years.

The FDA has approved a higher-dose injectable formulation of the long-acting glucagon-like peptide-1 (GLP-1) receptor agonist semaglutide (Ozempic) for treatment of type 2 diabetes in adults. A single SC injection of the new 8 mg/3 mL formulation delivers 2 mg of semaglutide.

In recently published clinical trials, once-weekly subcutaneous injection of the glucagon-like peptide 1 (GLP-1) receptor agonist semaglutide (Ozempic – Novo Nordisk), which is FDA-approved for treatment of type 2 diabetes and to reduce the risk of major adverse cardiovascular events in adults with type 2 diabetes and established cardiovascular disease, has reduced body weight significantly in patients with and without type 2 diabetes when given in addition to lifestyle intervention. Liraglutide (Saxenda), another GLP-1 receptor agonist, has been FDA-approved for chronic weight management since 2015.

Diet, exercise, and weight loss can improve glycemic control, but almost all patients with type 2 diabetes eventually require drug therapy. Treating to a glycated hemoglobin (A1C) concentration of <7% can prevent microvascular complications (retinopathy, nephropathy, and neuropathy), but whether it prevents macrovascular complications and death is unclear. An A1C target of <8% may be appropriate for older patients and those with underlying cardiovascular disease (CVD), a history of severe hypoglycemia, diabetes-related complications, a limited life expectancy, or a long duration of disease.

An oral formulation of the glucagon-like peptide-1 (GLP-1) receptor agonist semaglutide (Rybelsus – Novo Nordisk) has been approved by the FDA for once-daily treatment of type 2 diabetes in adults. Semaglutide, which has been available in a subcutaneously-injected formulation (Ozempic) since 2017, is the first GLP-1 receptor agonist to become available for oral administration; the 4 other GLP-1 receptor agonists currently available in the US are administered by subcutaneous (SC) injection.

Since 2008, because of safety concerns, the FDA has mandated that long-term cardiovascular outcomes trials be conducted for all new drugs for type 2 diabetes. Reductions in the incidence of macrovascular complications in these trials with some sodium-glucose co-transporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists in patients at risk for cardiovascular disease (see Table 1) have led to new recommendations.

The FDA has approved semaglutide (Ozempic – Novo Nordisk), a long-acting injectable GLP-1 (glucagon-like peptide-1) receptor agonist, for once-weekly treatment of adults with type 2 diabetes. It is the sixth GLP-1 receptor agonist to be approved in the US.