The FDA approved tirzepatide (Mounjaro) injection to improve glycemic control in adults with type 2 diabetes (T2D), as an adjunct to diet and exercise. Tirzepatide was effective at improving blood glucose and was more effective than the other diabetes therapies with which it was compared in clinical studies. Tirzepatide is NOT indicated for use in patients with type 1 diabetes.
Tirzepatide is a first-in-class medication that activates both the glucagon-like peptide (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors, which leads to improved blood glucose control. It is administered by subcutaneous injection once weekly, with the dose adjusted as tolerated to meet blood glucose goals.
Five clinical trials evaluated three different doses (5 mg, 10 mg, 15 mg) of tirzepatide as either standalone therapy or as an add-on to other diabetes medicines. The efficacy of tirzepatide was compared with placebo, semaglutide (a GLP-1 receptor agonist), and two long-acting insulin analogs. On average, patients randomized to receive the maximum recommended dose of tirzepatide (15 mg) had lowering of their hemoglobin A1c (HbA1c) level by 1.6% more than placebo when used in combination with a long-acting insulin. In trials comparing tirzepatide to other diabetes medications, patients who received the maximum recommended dose of tirzepatide had lowering of their HbA1c by 0.5% more than semaglutide, 0.9% more than insulin degludec, and 1.0% more than insulin glargine.
In clinical trials, adverse events associated with tirzepatide included nausea, vomiting, diarrhea, decreased appetite, constipation, upper abdominal discomfort, and abdominal pain. Tirzepatide causes thyroid C-cell tumors in rats. It is unknown whether tirzepatide causes such tumors, including medullary thyroid cancer, in humans. Tirzepatide should not be used in patients with a personal or family history of medullary thyroid cancer or in patients with multiple endocrine neoplasia syndrome type 2.
WEIGHT LOSS
Obesity was common among study participants (average body mass index of 32 to 34 kg/height m2 reported at the time of enrollment). More than half of patients taking the two highest doses of tirzepatide as a once-weekly injection lost at least 20% of their body weight in the first phase 3 trial to examine tirzepatide in patients with obesity but who did not have diabetes.
For prescribing information, consult product labeling.