Tirzepatide is a once‑weekly injection that hits both GLP‑1 and GIP receptors, giving stronger blood‑sugar drops and more weight loss than semaglutide or insulin in dose‑dependent studies (5, 10, 15 mg). Side effects are mainly stomach‑related early on, so a slow 4‑week titration is advised. In Belgium it’s reimbursed for people with BMI ≥ 30 and HbA1c > 7.5% on metformin, matching GLP‑1 rules but a bit stricter than EU label.

Tirzepatide is a unimolecular dual agonist of both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors, recently commercialized and reimbursed in Belgium for the treatment of type 2 diabetes (T2D). Because of the complementarity of action of the two incretins, tirzepatide showed, in a dose-dependent manner (5, 10 and 15 mg as a once-weekly subcutaneous injection), a better efficacy (greater reduction in HbA1c and body weight) compared with placebo, semaglutide 1 mg, basal insulin and preprandial boluses of insulin lispro in six studies of the SURPASS programme. Tirzepatide tolerance is almost similar to that of pure GLP-1 receptor agonists, with digestive adverse events, most often during the first weeks after initiation, which justifies the recommendation of progressive titration every four weeks. Tirzepatide is now refunded under conditions in Belgium for the treatment of TD2 in patients with a body mass index ≥ 30 kg/m² and a HbA1c level > 7.5 % with antihyperglycaemic therapy including metformin. These reimbursement conditions are similar to those of pure GLP-1 receptor agonists but are more restrictive than the indications validated by the European Medicines Agency and the latest guidelines by international scientific societies.