What is a GLP-1? The hormone, the medicines and the jargon
GLP‑1, incretin, agonist, GIP, dual agonist and DPP‑4 in plain words. And why no GLP‑1 medicine is really a "GLP‑1 inhibitor".
Written for India. Reading from the US? US versionComing soon
GLP‑1 (glucagon-like peptide-1) is a hormone your gut releases after you eat. The name also covers medicines that copy it, called GLP‑1 receptor agonists, like semaglutide. Tirzepatide also copies a second gut hormone, GIP. None of these blocks GLP‑1, so "GLP‑1 inhibitor" is a loose name for them. DPP‑4 inhibitors (gliptins) are different diabetes tablets.
Key takeaways
- GLP‑1 stands for glucagon-like peptide-1, a hormone made in the gut after a meal, and the same name is used for medicines that copy it.1, 16
- Semaglutide is a GLP‑1 receptor agonist: the US label says it is 94% the same as human GLP‑1 and switches on the same receptor.4
- Tirzepatide is a dual agonist that switches on both the GIP and the GLP‑1 receptors, according to its US label and its Indian marketer, Cipla.5, 6
- DPP‑4 inhibitors such as sitagliptin, vildagliptin and teneligliptin are diabetes tablets that slow the breakdown of your own GLP‑1, and US guidance rates them weight neutral.8, 9, 13
- In a 26-week trial, liraglutide lowered HbA1c (average blood sugar) by 1.5 points vs 0.9 on sitagliptin, but 27% felt sick (nausea) vs 5%.12
On this page
- What does GLP‑1 stand for, and what is it?
- What is an incretin, and where does GIP fit in?
- What does "agonist" mean in "GLP‑1 agonist"?
- What is a dual agonist, and what is a triple agonist?
- Which GLP‑1 medicines does India's government list?
- Is there such a thing as a "GLP‑1 inhibitor"?
- How do GLP‑1 agonists and DPP‑4 inhibitors differ?
- What do all the GLP‑1 terms mean, in one list?
- Questions people ask
- How we researched this
What does GLP-1 stand for, and what is it?
GLP‑1 stands for glucagon-like peptide-1. It is a hormone that cells in your gut release after you eat.
A peptide is a short chain of amino acids, the building blocks of proteins.3 The gene that makes glucagon, a hormone from the pancreas, also carries two "glucagon-like" pieces. That is where the names GLP‑1 and GLP‑2 come from.1
GLP‑1 is made by L cells along your small and large intestine. There are more of them lower down, near the end of the small intestine.1 Your own GLP‑1 lasts only 1 to 2 minutes before DPP‑4 breaks it down.2 DPP‑4 is an enzyme: a protein that speeds up chemical reactions in the body.3
Today the name also covers medicines that copy the hormone. India's government calls them "GLP‑1 drugs".16 For the short version, see our answer What is the full form of GLP‑1?
The medicines work like the hormone. When blood sugar is high, they boost insulin and cut glucagon, which raises sugar. They also slightly slow how fast your stomach empties after a meal.4 India's government says this keeps people fuller, so they feel less hungry.16 More in our guide What do GLP‑1 medicines do?
What is an incretin, and where does GIP fit in?
An incretin is a gut hormone released after food. It makes your pancreas release more insulin when sugar is high. GLP‑1 and GIP are the two known incretins.
GIP stands for glucose-dependent insulinotropic polypeptide. "Insulinotropic" just means "boosts insulin". GIP is made by K cells in the first part of the small intestine.1 Its older name was gastric inhibitory polypeptide.1
Swallowed sugar makes your body release 2 to 3 times more insulin than the same sugar given by drip. This is called the incretin effect, and GIP and GLP‑1 cause it.1
In type 2 diabetes, the incretin effect is weaker or gone. But GLP‑1 still works when you give more of it. That is why GLP‑1, not GIP, became the starting point for diabetes medicines.1 A 2018 review found that GIP alone had almost no effect on insulin in people with type 2 diabetes.1 Even so, the newer medicine tirzepatide is built on GIP, as the next sections explain.5
What does "agonist" mean in "GLP-1 agonist"?
An agonist is a medicine that fits into a receptor and switches it on, like the body's own hormone. A GLP‑1 agonist switches on the GLP‑1 receptor.
A receptor is a molecule on or inside a cell. When the right substance binds to it, the cell responds.3 Think of the receptor as a lock and GLP‑1 as its key. An agonist is a copied key: it binds the receptor and causes the same action as the natural substance.3
The full name is "GLP‑1 receptor agonist", often shortened to GLP‑1 RA.13 India's government uses the same term for these medicines.15, 16
You will also see "GLP‑1 analogue". An analogue is a modified copy. Semaglutide is a GLP‑1 analogue that is 94% the same as human GLP‑1 and acts as a receptor agonist.4 The changes make it stick to albumin, a protein in your blood, so it lasts far longer.4
The names give a clue. The World Health Organization (WHO) gives GLP analogues names ending in -glutide: liraglutide, dulaglutide, semaglutide.9 But not every GLP‑1 agonist ends that way. Tirzepatide doesn't, and neither does orforglipron, a newer daily pill from Lilly.7, 17 Orforglipron is not a peptide at all.17
What is a dual agonist, and what is a triple agonist?
A dual agonist switches on two receptors at once. Tirzepatide is the one sold in India: it switches on both the GIP and the GLP‑1 receptors.
- These are prescription-only medicines in India. They can't be bought over the counter.15, 16
- A government statement on 1 Apr 2026 said only endocrinologists, internal-medicine specialists and cardiologists can prescribe them.15, 16 CDSCO expert-committee minutes attach a similar condition to some approvals (endocrinologist or internal-medicine specialist), but we found no rule covering every brand.19
- Every medicine named here has risks: see Guide 5: Side effects and risks.
- Recalls and fake pens: Guide 6.
- Names below are facts, not recommendations. No medicine guarantees any result.
The US label calls tirzepatide "a GIP receptor and GLP‑1 receptor agonist". It is built on the GIP sequence, and you inject it once a week.5 In India it is sold as Mounjaro by Eli Lilly and as Yurpeak by Cipla, Lilly's second brand here.6 More in What is tirzepatide?
So is Mounjaro a GLP‑1? Partly. It acts on the GLP‑1 receptor, plus GIP. The American Diabetes Association (ADA) lists it as its own group, "dual GIP and GLP‑1 RA".13
A triple agonist acts on three hormone receptors. Retatrutide, made by Lilly, is one. It is still experimental. Lilly said on 5 August 2026 that it plans to apply for US approval in early 2027.7 We found no approval for it in India. More in What is the retatrutide injection, and is it available in India?
Which GLP-1 medicines does India's government list?
A government backgrounder of 1 April 2026 lists semaglutide (injection and tablets), liraglutide, tirzepatide, dulaglutide and exenatide as GLP‑1 medicines in the market.
The list, in the backgrounder's words, covers medicines "available in the market currently":16
- semaglutide injection
- semaglutide tablets
- liraglutide
- tirzepatide
- dulaglutide
- exenatide, including an extended-release form
Most come in pre-filled injection pens. Oral semaglutide is a tablet.16 We keep the backgrounder's order. It is not a ranking. The backgrounder doesn't say each one is on sale in India today.
Brand names you may see in India: semaglutide is sold as Ozempic, Wegovy and Rybelsus.14, 20 Tirzepatide is sold as Mounjaro and Yurpeak.6 These are facts, not recommendations. More in Is semaglutide the same as Ozempic? and Mounjaro vs Ozempic: how do they differ in India?
Generic semaglutide reached India on 20 March 2026, the day key patents expired.18 More in What changed for Ozempic when semaglutide's patent expired in India?
Orforglipron, the newer pill, is not on the list. An Indian expert committee recommended it for import and marketing on 20 May 2026. It added that shops should sell it only on an endocrinologist's or internal-medicine specialist's prescription.19, 17 We found no launch in India yet. In the US it is sold as Foundayo.7
Answer a few questions and see what India's guidance says a doctor may consider. No sign-up.
Is there such a thing as a "GLP-1 inhibitor"?
We found no GLP‑1 medicine that blocks GLP‑1. The ones on the government's list all copy it, so "GLP‑1 inhibitor" is a loose name for agonists.
An inhibitor blocks something. GLP‑1 medicines don't block GLP‑1; they copy it and switch on its receptor.4 India's government calls them "glucagon-like peptide-1 receptor agonists".16 Even its own backgrounder shortens this to "GLP‑1 drugs".16
Some people may mean a real inhibitor: DPP‑4 inhibitors, called gliptins. These diabetes tablets block DPP‑4, the enzyme that destroys your own GLP‑1 and GIP within minutes.8
With DPP‑4 blocked, your own incretins last longer. On the US sitagliptin label, active GLP‑1 and GIP rose 2 to 3 times after a meal.8 That is a moderate rise. GLP‑1 agonists push GLP‑1 activity far beyond what your body makes on its own.1
WHO gives DPP‑4 inhibitors names ending in -gliptin: sitagliptin, vildagliptin, teneligliptin, linagliptin, saxagliptin.9
SGLT2 inhibitors, called gliflozins, are another group of diabetes tablets.11 Their names end in -gliflozin, like dapagliflozin and empagliflozin.9 They are not GLP‑1 medicines either.
And watch the sulfonylureas, older tablets with names starting "gli-", like glimepiride and gliclazide.9 They can cause low blood sugar and weight gain.13 Brand names can mislead, so read the generic name printed on the strip.
How do GLP-1 agonists and DPP-4 inhibitors differ?
Both work through GLP‑1, but agonists act far more strongly. In US guidance, agonists lower sugar more and cause weight loss; gliptins are milder and weight neutral.
| GLP‑1 receptor agonists | DPP‑4 inhibitors (gliptins) | |
|---|---|---|
| How they work | Copy GLP‑1 and switch on its receptor4 | Slow the breakdown of your own GLP‑1 and GIP8 |
| How you take them | Mostly injections; semaglutide also comes as a daily tablet (Rybelsus)13, 14 | Tablets, for example sitagliptin 100 mg once a day8 |
| Lowering blood sugar | High to very high13 | Intermediate13 |
| Weight | Loss13 | Neutral13 |
| Name ending | Usually -glutide (tirzepatide and orforglipron differ)9, 17 | -gliptin9 |
Ratings from the ADA Standards of Care in Diabetes 2026, Table 9.2 (US guidance). Medicine classes only, not a recommendation.
One trial compared them head to head. 665 people with type 2 diabetes, already on metformin, were assigned liraglutide (a GLP‑1 agonist) or sitagliptin for 26 weeks.12 HbA1c is a blood test of your average sugar over the past few months. It started at about 8.5%.12
The trial was open-label (everyone knew which medicine they took) and paid for by Novo Nordisk, which makes liraglutide.12 Mild low-sugar episodes happened in about 5% of each group.12
- Stomach effects are common on GLP‑1 agonists. On Ozempic, 16% to 20% had nausea, vs 6% on a dummy injection (US label).4
- Pancreatitis (a swollen, painful pancreas) has been seen, sometimes fatal. The warning sign is severe stomach pain that won't go, sometimes spreading to the back.4
- Gallbladder problems, such as gallstones, have been reported.4
- Dehydration from vomiting or diarrhoea can injure the kidneys.4
- Thyroid warning. Semaglutide caused thyroid tumours in rodents. The US label rules it out for people with a personal or family history of medullary thyroid cancer or MEN 2; tell your doctor if this applies.4 Pregnancy: a possible risk to the baby.4
- Gliptins have their own risks: pancreatitis, severe joint pain and a blistering skin condition. Two gliptins were linked to heart failure in large trials.8
- Low sugar. Both groups raise the risk of low blood sugar when taken with insulin or sulfonylureas.4, 8
What do all the GLP-1 terms mean, in one list?
GLP‑1 is the gut hormone, agonists copy it, and DPP‑4 inhibitors make your own GLP‑1 last longer. The other terms follow.
- GLP‑1
- Glucagon-like peptide-1. A gut hormone released after eating. Also used loosely for the medicines that copy it.1, 16
- GIP
- Glucose-dependent insulinotropic polypeptide. The other gut hormone that boosts insulin after a meal.1
- Incretin
- A gut hormone that makes the pancreas release more insulin when sugar is high. GLP‑1 and GIP are incretins.1
- Receptor
- The "lock" on a cell that a hormone or medicine binds to.3
- Agonist
- A medicine that binds a receptor and switches it on, like the natural hormone.3
- Antagonist
- A substance that blocks an action. Not how GLP‑1 medicines work.3
- Analogue
- A modified copy of a natural molecule. Semaglutide is a GLP‑1 analogue.4
- Dual agonist
- Switches on two receptors. Tirzepatide: GIP and GLP‑1.5
- Triple agonist
- Switches on three receptors. Retatrutide, still experimental.7
- GLP‑1 inhibitor
- A loose name. No GLP‑1 medicine on India's government list blocks GLP‑1; they all copy it.16
- Enzyme
- A protein that speeds up chemical reactions in the body.3
Questions people ask
What is the full form of GLP-1?
Glucagon-like peptide-1. It is a hormone your gut releases after you eat.1
Is a GLP-1 agonist the same as a GLP-1 inhibitor?
No. A GLP‑1 agonist copies GLP‑1 and switches on its receptor.4 The GLP‑1 medicines on India's government list are all agonists, so "GLP‑1 inhibitor" is a loose name for them.16 Some people may mean DPP‑4 inhibitors (gliptins), tablets that slow the breakdown of your own GLP‑1.8
Is sitagliptin a GLP-1 drug?
Not exactly. Sitagliptin is a DPP‑4 inhibitor. It raises your own GLP‑1 and GIP 2 to 3 times after a meal, but it doesn't copy GLP‑1.8 US guidance rates it weight neutral.13
Is Mounjaro a GLP-1?
Mounjaro (tirzepatide) is a dual agonist. It switches on the GLP‑1 receptor and the GIP receptor.5
What is a GLP-1 antagonist?
An antagonist blocks a receptor instead of switching it on.3 GLP‑1 receptor antagonists such as exendin 9-39 are used in research.1 The GLP‑1 medicines prescribed in India are agonists.15, 16
Are GLP-1 medicines only injections?
No. Most come in pre-filled injection pens.16 But oral semaglutide (Rybelsus) is a GLP‑1 agonist tablet for type 2 diabetes in India.14, 15
How we researched this
On 5 October 2026 we read a 2018 review of the incretin hormones and a 2019 review of GLP‑1. We also read the US labels for Ozempic, Mounjaro and Januvia (sitagliptin). We used the 2026 ADA diabetes standards and WHO's drug-naming guide. The labels are American, not Indian; we say so where we use them.
For India we used a 2016 teneligliptin study and dated Business Standard and Medical Dialogues reports. We also used Cipla's launch release, the government statement and backgrounder of 1 April 2026, and CDSCO expert-committee minutes. Those minutes attach a prescriber condition to some approvals, but we found no rule covering every brand.
We left out a few things we could not source well. These include gliptin tablet prices, which were old and not MRPs. We also cut the weight results from the liraglutide vs sitagliptin trial. They sit behind a paywall we did not open.
Before you move on
- GLP‑1 is a gut hormone. "A GLP‑1" can also mean a medicine that copies it.
- An agonist switches a receptor on. Tirzepatide is a dual agonist: GIP plus GLP‑1.
- "-gliptin" tablets are DPP‑4 inhibitors, not GLP‑1 agonists. They are milder and don't usually change weight.
- Both groups carry risks, including pancreatitis. Read the generic name on any strip or pen.
More from the India blog
The monthly India update
An independent guide to GLP‑1 medicines. We don't sell medicines, take drug-company money or earn clinic commissions. Once a month: new brands, price changes, approvals and recalls. How we write
Sources
- Nauck MA, Meier JJ. Incretin hormones: their role in health and disease. Diabetes, Obesity and Metabolism, 2018;20(Suppl 1):5–21. doi:10.1111/dom.13129 · PMID 29364588
- Müller TD et al. Glucagon-like peptide 1 (GLP‑1). Molecular Metabolism, 2019;30:72–130 (section 5, GLP‑1 degradation). doi:10.1016/j.molmet.2019.09.010 · PMID 31767182
- National Cancer Institute (US). Dictionary of Cancer Terms: receptor, agonist, antagonist, peptide, enzyme. Accessed 5 October 2026.
- Novo Nordisk. Ozempic (semaglutide) prescribing information, US label (FDA), June 2026. Not the Indian label. Sections 5, 6.1, 8.1, 12.1. DailyMed
- Eli Lilly. Mounjaro (tirzepatide) prescribing information, US label (FDA), label revised August 2026, published on DailyMed September 2026. Not the Indian label. Sections 11, 12.1. DailyMed
- Cipla. Cipla launches Yurpeak (tirzepatide) for the treatment of obesity and type 2 diabetes. Press release, Mumbai, 10 December 2025. PDF
- Eli Lilly and Company. Lilly reports second-quarter 2026 financial results. 5 August 2026 (SEC Form 8-K, Exhibit 99.1). SEC
- Merck Sharp & Dohme. Januvia (sitagliptin) prescribing information, US label (FDA), November 2025. Not the Indian label. Sections 2, 5, 12.1–12.2, 14. DailyMed
- World Health Organization. The use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances (Stem Book 2018). WHO/EMP/RHT/TSN/2018.1. Entries -glutide, -gliptin, -gliflozin, gli-. PDF
- Ghosh S et al. Teneligliptin real-world efficacy assessment of type 2 diabetes mellitus patients in India (TREAT-INDIA study). Diabetes, Metabolic Syndrome and Obesity, 2016;9:347–353. doi:10.2147/DMSO.S121770 · PMID 27877058
- Business Standard. Going off-patent, key diabetes drug likely to get 50-70% cheaper. 8 July 2022. Link
- Pratley RE et al. Liraglutide versus sitagliptin for patients with type 2 diabetes who did not have adequate glycaemic control with metformin: a 26-week, randomised, parallel-group, open-label trial. Lancet, 2010;375:1447–56. Funded by Novo Nordisk. doi:10.1016/S0140-6736(10)60307-8 · PMID 20417856
- American Diabetes Association. 9. Pharmacologic approaches to glycemic treatment: Standards of Care in Diabetes—2026. Diabetes Care, 2026;49(Suppl 1):S183. US guidance. Table 9.2 and recommendation 9.18. doi:10.2337/dc26-S009 · PMID 41358900
- Medical Dialogues. Novo Nordisk gets CDSCO panel nod for Rybelsus label update, aligned with EMA. 10 September 2025. Link
- Outlook India (PTI). Inspections, surveillance to continue against unauthorised sale, promotion of GLP‑1 weight-loss drugs: govt. 1 April 2026. Link
- Press Information Bureau (Government of India), PIB Research. GLP‑1 Drugs: Use, Risks, and Regulation. Backgrounder, 1 April 2026. PDF
- Medical Dialogues. Eli Lilly's Orforglipron Tablet gets CDSCO Panel Nod for Import, Marketing in India. 8 June 2026. Link
- BusinessToday. NATCO opens semaglutide market at ₹1,290, sets early price benchmark. 20 March 2026. Link
- CDSCO. Recommendations of the Subject Expert Committee (Endocrinology & Metabolism): 20–21 April 2023 · archived copy (tirzepatide) and 13–14 February 2024 · archived copy (semaglutide), and 20 May 2026 · archived copy (orforglipron, 13th/26 meeting, item 4). Committee minutes, not final permissions.
- ThePrint (Reuters). Novo Nordisk again cuts Ozempic, Wegovy prices by up to 48% in India as generics flood market. 1 April 2026. Link
Last checked 5 Oct 2026 · Next review due 5 Oct 2027 · Report an error
How this post was made. Written by the GLP Guidebook team from the sources above. It's general information, not medical advice. Talk to a qualified doctor before starting, stopping or changing any medicine. How we write