Key takeaways
Metformin (Glumetza, Riomet) and tirzepatide (Mounjaro) are both medications used to manage Type 2 diabetes. However, they belong to different medication classes and have distinct mechanisms of action. Metformin is a biguanide that works by lowering the amount of sugar your body makes and improving insulin use in the body. It is taken orally, usually once or twice a day, and is available in both short-acting and long-acting forms. Tirzepatide, on the other hand, is a glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist that mimics gut hormones to control blood sugar. It is administered as a subcutaneous (under the skin) injection once a week. While metformin is available as a lower-cost generic, tirzepatide is only available as a brand-name medication. Common side effects of both medications include diarrhea, stomach upset, and nausea. Additionally, tirzepatide has a risk of causing thyroid cancer and pancreatitis, which are not associated with metformin. Both medications can cause low blood sugar, especially when used with other diabetes treatments, but metformin is less likely than tirzepatide to cause this when used alone.
