Tirzepatide (approved 2022) demonstrates superior HbA1c reduction compared to GLP-1 receptor agonists alone. Its additional mechanism compared to semaglutide is:
- A Combined GLP-1 receptor agonism plus DPP-4 inhibition, preserving endogenous GLP-1
- B Triple GLP-1 + GIP + glucagon receptor agonism (GLP-1/GIP/GCG triagonism)
- C GLP-1 receptor agonism combined with SGLT2 inhibition in a single molecule
- D Dual GIP (glucose-dependent insulinotropic polypeptide) receptor plus GLP-1 receptor agonism — GIP receptor activation enhances glucagon suppression and adipose tissue lipolysis inhibition beyond GLP-1 alone ✓
Explanation
Tirzepatide is the first approved dual GIP/GLP-1 receptor agonist (twincretin). GIP (glucose-dependent insulinotropic polypeptide) was previously considered to have blunted effect in T2DM, but pharmacological GIP receptor activation in combination with GLP-1 agonism produces synergistic insulin secretion, superior weight loss (partly through GIP's role in adipose lipogenesis inhibition), and better glycemic control. GIP receptor activation also reduces nausea (a key GLP-1 side effect), improving tolerability. SURPASS trials showed tirzepatide's superiority over semaglutide. Triple GLP-1/GIP/glucagon agonism (retatrutide) is in phase III but not yet approved.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.