FDA Approves First-in-Class Treatment for Type 2 Diabetes

Mounjaro is a first-in-class once-weekly, dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist.

The Food and Drug Administration (FDA) has approved Mounjaro™ (tirzepatide) as an adjunct therapy to diet and exercise to improve glycemic control in adults with type 2 diabetes. 

Mounjaro is a first-in-class, once-weekly, dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist that integrates the actions of both incretins into a single molecule. It enhances first- and second-phase insulin secretion, and reduces glucagon levels, both in a glucose-dependent manner.

The approval was based on data from the SURPASS clinical program, which included 5 clinical trials that assessed the efficacy and safety of Mounjaro as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes. In these trials, Mounjaro was studied as stand-alone therapy (SURPASS-1 [ClinicalTrials.gov Identifier: NCT03954834]); as an add-on to metformin, sulfonylureas, and/or sodium-glucose co-transporter 2 inhibitors (SGLT2 inhibitors) (SURPASS-2, -3, and -4 [ClinicalTrials.gov Identifier: NCT03987919, NCT03882970, NCT03730662]); and in combination with basal insulin with or without metformin (SURPASS-5 [ClinicalTrials.gov Identifier: NCT04039503]).

Results from these trials showed that treatment with Mounjaro resulted in statistically significant reduction in HbA1c (primary endpoint) compared with placebo, semaglutide, insulin degludec, and insulin glargine. Mounjaro also led to significantly greater weight reductions vs the comparators (secondary endpoint). The most common adverse reactions reported were nausea, vomiting, diarrhea, decreased appetite, constipation, dyspepsia, and abdominal pain.

“Given the challenges many patients experience in achieving their target blood sugar goals, today’s approval of Mounjaro is an important advance in the treatment of type 2 diabetes,” said Patrick Archdeacon, MD, associate director of the Division of Diabetes, Lipid Disorders, and Obesity in the FDA’s Center for Drug Evaluation and Research.

Mounjaro carries a Boxed Warning associated with the risk of thyroid C-cell tumors in rats; it is unknown whether the drug can cause these tumors, including medullary thyroid cancer (MTC), in humans. The use of Mounjaro is contraindicated in patients with a personal or family history of MTC or in patients with multiple endocrine neoplasia syndrome type 2.

Mounjaro has not been studied in patients with a history of pancreatitis and is not indicated for use in patients with type 1 diabetes mellitus.

The product is supplied in 6 doses: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, or 15mg per 0.5mL, as prefilled single-dose pens for subcutaneous injection. It is expected to be available in the coming weeks.


  1. FDA approves novel, dual-targeted treatment for type 2 diabetes. News release. US Food and Drug Administration. May 13, 2022. Accessed May 16, 2022. https://www.fda.gov/news-events/press-announcements/fda-approves-novel-dual-targeted-treatment-type-2-diabetes.
  2. FDA approves Lilly’s Mounjaro™ (tirzepatide) injection, the first and only GIP and GLP-1 receptor agonist for the treatment of adults with type 2 diabetes. News release.  Eli Lilly and Company. May 13, 2022. Accessed May 16, 2022. https://investor.lilly.com/news-releases/news-release-details/fda-approves-lillys-mounjarotm-tirzepatide-injection-first-and.
  3. Mounjaro. Package insert. Eli Lilly and Company; 2022. Accessed May 16, 2022. https://pi.lilly.com/us/mounjaro-uspi.pdf.