# Tirzepatide: A Clinical Literature Digest of the Dual GIP/GLP-1 Record > Tirzepatide is an FDA-approved dual GIP and GLP-1 receptor agonist. Independent summaries of the SURPASS, SURMOUNT, SYNERGY-NASH, SURMOUNT-OSA, and SUMMIT trials — cited to source. Independent summaries of the SURPASS, SURMOUNT, SYNERGY-NASH, SURMOUNT-OSA, and SUMMIT trial programmes, with every quantitative finding cited to source. ## The short version Tirzepatide is a prescription medicine, FDA-approved in 2022 for type 2 diabetes and in 2023 for weight management. It is a synthetic peptide — a short chain of amino acids — that works by activating two receptors in the body at the same time: one called GIP and one called GLP-1. Both receptors are part of the body's normal system for managing blood sugar after a meal. Activating both together helps the body release insulin when blood sugar rises, suppresses glucagon (the hormone that raises blood sugar), slows digestion, and reduces appetite. In large clinical trials, tirzepatide reduced body weight by up to 20.9 percent in people with obesity, and cut HbA1c — a key blood sugar marker — by more than 2 percentage points in people with type 2 diabetes. More recent trials have found benefits for obstructive sleep apnea, fatty liver disease, and heart failure. Side effects are real, mostly gastrointestinal, and are covered in detail on [the effects page](/effects). ## What the Tirzepatide trials have established Tirzepatide is a 39-amino-acid synthetic peptide classified as a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. It received its first FDA approval for type 2 diabetes in May 2022 and a second approval for chronic weight management in November 2023 [7]. The agent is also approved for moderate-to-severe obstructive sleep apnea in adults with obesity. The SURPASS phase 3 programme established tirzepatide's glycaemic profile across type 2 diabetes populations. In SURPASS-2, the head-to-head trial against semaglutide 1 mg (n=1,879, 40 weeks), tirzepatide at all three doses — 5, 10, and 15 mg once weekly — was noninferior and superior to semaglutide for HbA1c reduction (estimated reductions of -2.01, -2.24, and -2.30 percentage points, versus -1.86 with semaglutide), and produced greater body-weight reductions of 1.9, 3.6, and 5.5 kg more than semaglutide [3]. The SURMOUNT programme addressed obesity. SURMOUNT-1 (n=2,539, 72 weeks, adults with obesity or overweight without diabetes) produced mean weight changes of -15.0%, -19.5%, and -20.9% at 5, 10, and 15 mg once weekly versus -3.1% with placebo [4]. In SURMOUNT-5, a direct head-to-head against semaglutide in 751 adults with obesity, tirzepatide reduced weight by -20.2% versus -13.7% with semaglutide (P<0.001) [5]. Beyond blood sugar and weight, the trial programme has extended into liver disease, sleep apnea, and heart failure. Explore [Tirzepatide research](/research) for the full evidence breakdown, or see [tirzepatide weight loss](/weight-loss) for the obesity trial data in detail. ## The beyond-glycaemia story Three recent trials extended the evidence base into conditions beyond blood sugar management. In SYNERGY-NASH, adults with metabolic dysfunction-associated steatohepatitis (MASH) — a progressive form of fatty liver disease — who received once-weekly tirzepatide achieved MASH resolution without worsening of liver fibrosis at higher rates than placebo [8]. In SURMOUNT-OSA, adults with obesity and moderate-to-severe obstructive sleep apnea (a condition where breathing repeatedly stops during sleep, measured by the apnea-hypopnea index, or AHI) saw their AHI reduced by 25.3 events per hour (in patients not using a breathing device) and 29.3 events per hour (in those using one), versus roughly 5 events per hour with placebo over 52 weeks [9]. In the SUMMIT trial, tirzepatide reduced heart-failure events and improved outcomes in patients with heart failure with preserved ejection fraction (HFpEF — a form of heart failure where the heart pumps adequately but fills abnormally) and obesity [10]. This expanding portfolio of indications reflects the breadth of effects that dual GIP/GLP-1 receptor engagement produces across metabolic tissues. The [Tirzepatide references](/references) page carries the full citation list. ## What to read next This site is a clinical literature digest. It summarises the published trial evidence on Tirzepatide in plain English, with every quantitative claim cited to its source study. It is not a clinic. Nothing here is a dosing recommendation. - [What is tirzepatide](/what-is-tirzepatide) — the molecule, the mechanism, and the approved indications explained - [Tirzepatide weight loss](/weight-loss) — the SURMOUNT obesity trial evidence in detail - [Effects & what people report](/effects) — reported benefits, side effects, and safety cautions - [The science](/research) — mechanism, head-to-head data, and the full trial record - [Doses studied](/dosage) — the titration schedule and pharmacokinetics from the clinical programme - [Questions](/faq) — 22 common questions answered and cited --- A reading room for the published tirzepatide trial record — not a clinic, not a prescriber.