GLP-1: Byetta (exenatide)

An FDA-approved GLP-1 shot for type 2 diabetes, first approved in 2005. The weekly versions (Bydureon) are listed as discontinued.

AI illustration of an injector pen labeled Exenatide — AI illustration

FDA statusFDA approved

The FDA approved it as a prescription medicine for certain uses.

Proof it works in people for type 2 diabetesStrong

Trials showed better blood sugar.

Safety data in peopleWell studied

Years of use. Risks are on the FDA label.

These are 3 different questions. FDA status is about the law. Proof is about whether it works. Safety data is about how much we know about its risks. A lack of safety data does not mean it does not work, and "not approved" does not mean "illegal."

By the Peptide Science Desk Editorial TeamFact-checked against FDA and official sources · Oct 18, 2026Not yet reviewed by a licensed clinician. How we check facts

What is it?

Exenatide is a peptide medicine in the GLP-1 family, like semaglutide. The brand is Byetta, a twice-a-day shot. You need a prescription.

Why do people use it?

Doctors use Byetta, with diet and exercise, to help control blood sugar in adults with type 2 diabetes.

Does it really work?

This one is proven. The FDA first approved exenatide in 2005. The once-a-week versions, Bydureon and Bydureon BCise, are now listed by the FDA as discontinued. It is not approved for weight loss.

Studies in people

Study	People	What they found	Limits
Randomized trial	336	A1C dropped 0.78 points vs rising 0.08 on placebo in 30 weeks. Small weight loss.	Added to metformin.

We only list studies we read on PubMed or ClinicalTrials.gov. Checked October 18, 2026.

The numbers in a chart

How much 3 peptides lowered blood sugar (A1C)

Change in A1C in percentage points, drug vs placebo. A minus sign means lower (better)

Retatrutide 12 mgNot FDA approvedTRANSCEND-T2D-1 · 537 adults, type 2 · 40 weeks

−1.94

−0.81

Exenatide 10 µg (Byetta)336 adults, type 2, with metformin · 30 weeks

−0.78

+0.08

Pramlintide (Symlin) + insulin651 adults, type 1 · 52 weeks · 2 dose groups

−0.29 to −0.34

−0.04

Different trials, different people: not a head-to-head comparison. Type 1 and type 2 diabetes are different diseases.

Show the numbers as a table

How much 3 peptides lowered blood sugar (A1C): Change in A1C in percentage points, drug vs placebo. A minus sign means lower (better)
Drug	Drug	Placebo
Retatrutide 12 mg (Not FDA approved) TRANSCEND-T2D-1 · 537 adults, type 2 · 40 weeks	−1.94	−0.81
Exenatide 10 µg (Byetta) 336 adults, type 2, with metformin · 30 weeks	−0.78	+0.08
Pramlintide (Symlin) + insulin 651 adults, type 1 · 52 weeks · 2 dose groups	−0.29 to −0.34	−0.04

A1C shows average blood sugar over about 3 months. The striped bar means the placebo group's A1C went up a little. Sources: TRANSCEND-T2D-1, Lancet 2026 (PMID 42250575); DeFronzo et al., Diabetes Care 2005 (PMID 15855572); Ratner et al., Diabet Med 2004 (PMID 15498087).

More charts: Peptides by the numbers

Is it safe? Side effects

Common side effects on the label include feeling sick, low blood sugar, throwing up, diarrhea, feeling jittery, dizziness, headache, upset stomach, constipation, and weakness.
The label warns about pancreas swelling (pancreatitis).
Low blood sugar is more likely if it is used with insulin or some other diabetes pills.

Is it legal in the US?

Yes. Byetta is FDA-approved. (The FDA is the US agency that checks if medicines are safe and work.) The weekly Bydureon products are listed as discontinued.

What "not approved" does and does not mean

With a prescription, it is legal to use for the uses on its FDA label.
Doctors may also prescribe an approved drug for other uses ("off-label") when they think it is right for you. (FDA)
Copies made by a pharmacy (compounded) are not FDA approved. The FDA does not check them before they are sold. State boards of pharmacy oversee most pharmacies. (FDA)
Products sold online "for research" or "not for human use" are not the approved medicine. The FDA has warned companies that sold them to people. (FDA)

Banned in sports? Drug tests

Not banned in sports.

No. USADA says GLP-1 drugs like exenatide (Byetta) are not banned in sport, and no special medical exemption is needed.

Check work, NCAA, and military rules for Byetta

Talk to your doctor

Do not start any peptide on your own. Ask a doctor first. We never share doses or tell you where to buy. Print our doctor questions sheet.

Check any peptide in 1 secondFree FDA Status Checker: approved, being tested, or not proven.

Related peptides

Guides and tools

Sources

Not medical advice. Medical disclaimer.