The short answer: Sometimes, but only off-label and with close medical supervision. No GLP-1 drug is FDA-approved to treat type 1 diabetes, and insulin stays the core treatment. Trials show modest drops in A1C, insulin needs, and weight. They also show more low blood sugar and more ketosis, so any use needs a careful plan with a diabetes team.

What do the FDA labels say about type 1 diabetes?

Every GLP-1 drug sold for diabetes in the US is approved only for type 2 diabetes. The Ozempic (semaglutide) label, updated in June 2026, lists three uses. All three are in "adults with type 2 diabetes mellitus." The Mounjaro (tirzepatide) label, updated in August 2026, is also limited to type 2 diabetes in adults and in children 10 and older.

The current labels do not carry a separate warning line about type 1 diabetes. That does not make these drugs approved for it. Type 1 diabetes is simply outside the approved use, so any prescription for it is off-label.

The weight-loss versions are a different case. Wegovy and Zepbound are approved for chronic weight management in adults with obesity, or with overweight plus a weight-related condition. They do not exclude type 1 diabetes. But the Wegovy label states plainly: "The use of WEGOVY in patients with type 1 diabetes mellitus or in combination with insulin has not been evaluated."

Why do some doctors prescribe them off-label?

Type 1 diabetes is an autoimmune disease. The body makes little or no insulin, so a GLP-1 drug cannot replace insulin. To see what these drugs do in the body, read how GLP-1 drugs work. Clinicians still try them in some adults with type 1 diabetes for a few reasons:

  • Weight. Some adults with type 1 diabetes also live with overweight or obesity. Extra weight raises insulin resistance and heart risk.
  • Insulin dose. GLP-1 drugs slow stomach emptying, lower glucagon after meals, and cut appetite. That can lower the insulin a person needs, mainly at meals.
  • Glucose swings. Some people see smoother readings after meals and more time in their target range.

Off-label use is legal. It does mean the drug maker has not proven the benefit and safety for this group to the FDA. Insurers often deny coverage for an off-label use, so cost can be a real barrier. See our guide to GLP-1 insurance coverage for how appeals work.

What did the large liraglutide trials show?

The biggest trials used liraglutide (Victoza), an older daily GLP-1 drug. Two large placebo-controlled trials tested it in adults with type 1 diabetes.

ADJUNCT ONE (Diabetes Care, 2016) enrolled 1,398 adults for 52 weeks. At the top dose of 1.8 mg, A1C fell only 0.20 points more than placebo. Weight dropped 4.9 kg more than placebo, and insulin doses fell by about 8%. The rate of symptomatic low blood sugar rose about 31%. Episodes of high blood sugar with ketosis more than doubled at 1.8 mg.

ADJUNCT TWO enrolled 835 adults for 26 weeks, with insulin doses capped. At 1.8 mg, A1C fell 0.33 points versus almost no change on placebo. Weight fell 5.1 kg versus 0.2 kg. Hyperglycemia with ketosis was more common at 1.8 mg (0.5 versus 0.1 events per patient per year).

The ADJUNCT ONE authors concluded the higher rates of low blood sugar and ketosis limited clinical use. Liraglutide was never approved for type 1 diabetes.

What about semaglutide and tirzepatide?

Newer, stronger drugs have renewed interest. The best trial so far is ADJUST-T1D, published in NEJM Evidence in 2025. It enrolled 72 adults with type 1 diabetes, a BMI of 30 or higher, and an automated insulin delivery system (an insulin pump linked to a glucose sensor). Half took weekly semaglutide up to 1 mg for 26 weeks. Half took placebo.

  • 36% on semaglutide met a combined goal: over 70% time in range, under 4% time low, and at least 5% weight loss. No one on placebo met it.
  • Weight fell 8.8 kg more than placebo.
  • Time in range rose 8.8 percentage points, and A1C fell 0.3 points more than placebo.
  • Each group had two severe low blood sugar events. No diabetic ketoacidosis was reported.

That trial was small and short, and everyone used an automated pump that adjusts insulin on its own. The results may not apply to people on injections.

For tirzepatide, Eli Lilly is running SURPASS-T1D-1, a phase 3 placebo-controlled trial in adults with type 1 diabetes and obesity or overweight. It started in April 2025, with about 905 people planned. Primary completion is estimated for November 2026, so no results are out yet. For drug-specific details, see mounjaro.md.

What are the main safety risks?

Two risks stand out, and they pull in opposite directions.

Low blood sugar (hypoglycemia). The Ozempic label warns that use with insulin "may increase the risk of hypoglycemia, including severe hypoglycemia." It adds that "reducing dose of insulin secretagogue or insulin may be necessary." With lower appetite and slower digestion, a usual meal dose of insulin can be too much.

Diabetic ketoacidosis (DKA). If insulin is cut too far, the body can run short of it. MedlinePlus explains that DKA happens when insulin is so low that the body breaks down fat too fast, and ketones make the blood acidic. It is life-threatening. MedlinePlus lists missed insulin doses among its triggers in type 1 diabetes.

Common GLP-1 side effects still apply, including nausea, vomiting, and constipation. See our GLP-1 side effects guide. Some people should not take these drugs at all, such as people with a personal or family history of medullary thyroid cancer.

Practical safety steps a diabetes team often uses:

  1. Plan insulin changes before the first dose, not after a low.
  2. Use a continuous glucose monitor and review the data often.
  3. Have a way to check ketones, and know when to call for help.
  4. Do not stop or sharply cut basal insulin on your own.

What does the American Diabetes Association recommend now?

The American Diabetes Association released its Standards of Care in Diabetes 2026 in December 2025. One listed change is "new guidance on the treatment of obesity in people with type 1 diabetes." The Summary of Revisions adds GLP-1 RA-based therapy and metabolic surgery as options for adults with type 1 diabetes and obesity.

This is guidance for weight treatment, not for blood sugar control alone. It points toward the approved weight-loss products in people who meet obesity criteria. It does not make GLP-1 drugs a standard add-on for every person with type 1 diabetes.

The bottom line

GLP-1 drugs are not approved for type 1 diabetes, and they never replace insulin. For adults with type 1 diabetes and obesity, the ADA now lists them as a treatment option. Trials show real weight loss and modest glucose gains, with higher risks of low blood sugar and ketosis. If you want to try one, do it with an endocrinologist who can adjust insulin and watch your ketones.

Last updated: September 2026. This article is for informational purposes only and does not constitute medical advice. People with type 1 diabetes should never change insulin doses or start a GLP-1 drug without their diabetes care team.