Mounjaro® (tirzepatide) is a relatively new injectable medication developed by Eli Lilly. It is approved for type 2 diabetes and is under review/being used off-label for weight management.

What It Is

• Class: Dual GIP/GLP-1 receptor agonist

• Sometimes called a “twincretin” because it activates two gut hormone receptors:

  • GLP-1 (glucagon-like peptide-1) → improves insulin release, slows stomach emptying, reduces appetite

  • GIP (glucose-dependent insulinotropic polypeptide) → enhances insulin release and may improve fat metabolism

How It Works

• Lowers blood sugar by helping the pancreas release more insulin when glucose is high.

• Slows digestion so you feel full longer.

• Reduces appetite → significant weight loss effect.

Dosing

• Given as a weekly subcutaneous injection (stomach, thigh, or upper arm).

• Started at a low dose (e.g., 2.5 mg once weekly) and gradually increased up to 15 mg.

Uses

• Approved: Type 2 diabetes (to improve blood sugar control).

• Weight management: Not yet approved everywhere for obesity, but studies show very strong results (average 15–22% body weight loss, sometimes more than semaglutide/Wegovy).

Side Effects

Common:

• Nausea, vomiting, diarrhea, constipation

• Decreased appetite

• Fatigue

Serious (less common):

• Pancreatitis

• Gallbladder disease

• Low blood sugar (when combined with insulin/sulfonylureas)

• Contraindicated in people with personal/family history of medullary thyroid cancer or MEN2 (similar to semaglutide).

Effectiveness

• Lowers HbA1c by ~2% or more (stronger than most diabetes drugs).

• Weight loss is often greater than with semaglutide (Wegovy/Ozempic) in head-to-head trials.

✅ Bottom line: Mounjaro is a powerful new weekly injection for type 2 diabetes that also causes major weight loss. It may soon become a leading treatment for obesity, not just diabetes.