The active substance in Mounjaro, tirzepatide, acts in the same way as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).
These hormones are produced in the gut and bind to specific receptors (targets) in the body, such as, among others, the pancreas and brain. This increases the amount of insulin that the pancreas releases in response to food and helps lower blood glucose levels in people with type 2 diabetes.
Targeting these receptors also reduces appetite and helps people manage their weight.
Further information on Mounjaro is available in the in the Summary of Product Characteristics from the European Medicines Agency which is available here