Tirzepatide (Mounjaro): Type 2 Diabetes Drug Guide
Health ConditionsDiabetesType 2 Diabetes

Everything You Need to Know About Tirzepatide (Mounjaro) for Type 2 Diabetes

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Updated on May 8, 2026

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What’s the Difference Between Ozempic and Mounjaro?

Leading endocrinologist Caroline Messer, MD, offers her advice on the newest weight loss medications.

If you’re living with type 2 diabetes, you may have heard about new medications to help manage blood sugar, whether on TV, on social media, or from a friend. You may have also heard a lot of buzz about people using these drugs for weight loss — for example, tirzepatide is now sold as Zepbound when it’s prescribed to treat obesity. You may be wondering if tirzepatide is right for you, and how you can start this conversation with your doctor.

Here’s a primer on tirzepatide (sold as Mounjaro for type 2 diabetes).

What Is Tirzepatide and How Do GLP-1 and GIP Receptor Agonists Work?

Tirzepatide (Mounjaro and Zepbound) is the first U.S. Food and Drug Administration (FDA)–approved drug that is part of a new drug class called glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonists.

Tirzapetide is administered either as a once-weekly injection under the skin of your abdomen, thigh, or upper arm using a prefilled pen or as a pill, according to the manufacturer.

 Doses range from 2.5 milligrams (mg) to 15 mg.

“Mounjaro has to be titrated when it is started, meaning a gradual dose increase happens over many months, to allow the body to adjust to the medication and lower the risk of side effects,” says Florencia Halperin, MD, a Boston-based endocrinologist who is the chief medical officer of the weight loss clinic Form Health.

The Mechanism Behind GLP-1 and GIP Receptor Agonists

Not all of the mechanisms of this class of drugs are known yet. What is known is that the medications mimic the actions of two incretin hormones: GLP-1 (which is in the upper gut) and GIP (which is in the lower gut). The duo works together to stimulate insulin secretion after a meal is eaten, according to research and the American Diabetes Association.

The insulin then helps your body use or store glucose (sugar) in a way that the body can’t on its own due to type 2 diabetes. With type 2 diabetes, the body can’t handle insulin as efficiently as it should, and you can develop high blood sugar, or hyperglycemia.

The drug affects multiple organs in the body, mimicking and stimulating both the GIP and GLP-1 receptors in our bodies, Dr. Halperin says.

“These receptors are found in the pancreas, where stimulation leads to increased insulin secretion. They are also found in the appetite centers of the brain. GLP-1 also slows down stomach emptying, so people feel fuller sooner and longer. And GIP is known to act on our fat cells in a variety of ways,” Halperin says.

What’s the Difference Between Tirzepatide and Semaglutide?

The drug may sound similar to another type 2 diabetes and weight loss drug, semaglutide, which is a GLP-1 receptor agonist. Similar to tirzepatide, semaglutide — sold as the type 2 diabetes drug Ozempic and the obesity drug Wegovy — mimics the hormone GLP-1 and triggers the body to make more insulin when blood sugar levels rise after eating.

 GLP-1 receptor agonists are so popular that they were on the FDA’s shortage list in 2023, but have since been taken off.

Tirzepatide is different from semaglutide because it also mimics the GIP hormone. Meaning, it affects not only stomach emptying and appetite but also how fat is deposited in the body.

What Is Tirzepatide Approved to Treat?

In May 2022, the FDA approved Mounjaro for type 2 diabetes, and five months later, the agency gave it a fast-track designation to expedite the review of results from two phase 3 clinical trials investigating it as a weight loss treatment, according to Eli Lilly.

 Results from the second of those trials were released by Eli Lilly on April 27, 2023, and subsequently published online in The Lancet in June 2023.

In November 2023, the FDA approved tirzepatide for weight loss under the name Zepbound. Research has shown that tirzepatide helped people lose an average of 27 percent of their body weight over the course of a year and a half, when combined with diet and exercise.

Tirzepatide is not indicated for people with type 1 diabetes, according to the manufacturer. However, a recent 12-week clinical trial found that the medication was superior to placebo for weight loss in adults with type 1 diabetes. While promising, additional studies are needed.

Only your healthcare team can determine if these meds are a good fit for you, so be sure to consult them to discuss what’s right for your health and wellness goals.

Which Type 2 Diabetes Health Complications Can GLP-1 and GIP Receptor Agonists Help Treat?

Tirzepatide is FDA-approved for treating hyperglycemia (blood sugar that is too high), a symptom of type 2 diabetes.

The medication is currently being studied  in several trials for its effects relating to cardiovascular disease, and has been shown to improve many of its risk factors.

Currently, the drug is FDA-approved as a treatment for obesity, which is a risk factor for type 2 diabetes.

Which Brand-Name GLP-1 and GIP Receptor Agonists Have Been Approved by the FDA?

Currently, Mounjaro and Zepbound, and Trulicity (dulaglutide), are brand-name FDA-approved drugs for type 2 diabetes management. Other brand-name FDA-approved drugs include Ozempic (semaglutide), Rybelsus (semaglutide pills), and Victoza (liraglutide).

Research shows that other new GLP-1 and GIP receptor agonist drugs are in various early stages of development and are awaiting FDA approval.


What Are the Potential Benefits of GLP-1 and GIP Receptor Agonists?

Tirzepatide is shaping up to be a game-changer for people living with type 2 diabetes and obesity. That’s because it’s gained a solid body of peer-reviewed research and is highly effective for treating both conditions.

Better Blood Sugar Management in Type 2 Diabetes

So far, this class of drugs has shown significant effectiveness in the treatment of type 2 diabetes. This is based on the results of five randomized clinical trials cited by the FDA in its May 2022 statement announcing the approval of tirzepatide as a treatment for the disease, when used in combination with diet and exercise.

Hailing the approval as “an important advance in the treatment of type 2 diabetes,” the agency pointed out that on average, patients receiving the maximum recommended dose of Mounjaro (15 mg) saw their hemoglobin A1C levels lowered by 1.6 percentage points more than placebo when used as a stand-alone therapy, and 1.5 percentage points more than placebo when used in combination with a long-acting insulin.

 A1C is a two- to three-month average of blood sugar levels, according to the Centers for Disease Control and Prevention.

Other randomized clinical trials that compared tirzepatide with other type 2 diabetes medications found that tirzepatide improved outcomes. The maximum recommended dose of tirzepatide had lowered individuals’ A1C by 0.5 percentage points more than semaglutide, according to one study

; 0.9 percentage points more than the long-acting insulin degludec (Tresiba), according to another study

; and 1.0 percentage point more than another long-acting insulin glargine (Lantus), according to another study.

Weight Loss

Tirzepatide appears to be exceptionally effective for weight loss in people with and without type 2 diabetes, according to two clinical trials that tested its effectiveness for that use.

Nearly every participant in a 2022 study who received tirzepatide injections in conjunction with diet and exercise lost weight. The SURMOUNT-1 randomized trial involved more than 2,500 people who did not have diabetes but did have obesity (defined as a body mass index [BMI] of 30 and higher) or a weight-linked disease and a BMI of 27 and up.

Participants were randomly assigned to receive 5 mg, 10 mg, or 15 mg of tirzepatide or to receive placebo. Everyone also received an intervention that included regular lifestyle counseling sessions to help them adhere to “healthful, balanced meals,” with a deficit of 500 calories per day and at least 150 minutes of physical activity per week.

Not only did more than 97 percent of participants lose weight over 72 weeks, but more than one-third of the participants lost at least one-quarter of their body weight. The average weight reduction was 22.5 percent with the highest dose (15 mg), versus 2.4 percent in the placebo group. Furthermore, those who received the drug experienced a five times greater reduction in waist circumference than those who had the placebo (19.9 centimeters, or 7.8 inches, versus 3.4 centimeters, or 1.3 inches).

Another clinical trial assigned a randomized portion of adults who had obesity but not type 2 diabetes the highest dose of semaglutide — 2.4 mg — along with diet and exercise, versus lifestyle changes alone in the placebo group. At the end of five years, people on semaglutide had lost about 15 percent of their body weight on average — compared with about 2.4 percent in the placebo group.

In April 2023, Lilly announced the results of the second SURMOUNT trial, which studied tirzepatide’s effectiveness in people who had type 2 diabetes. Participants had a BMI of 27 or higher, weighed an average of 222 pounds (lb), and had an average A1C level of 8.0 at the start of the study. After 72 weeks, those who took the 10-mg dose of tirzepatide dropped an average of 30 lb, or 13.4 percent of their body weight, and those who took the 15-mg dose, lost an average of 34.4 lb, or 15.7 percent of their weight , compared with 7 lb, or a 3.3 percent weight loss, in those taking the placebo. More than four out of five of those taking a 10-mg or 15-mg dose lost at least 5 percent of their body weight, compared with 30.5 percent of those taking the placebo.

Improved Blood Pressure

Beneficial effects on systolic blood pressure (a measure of how much pressure is exerted against your artery walls when your heart is beating) have been found across the series of SURPASS trials that studied tirzepatide in people with type 2 diabetes. Systolic pressure dropped by between 4.2 mmHg and 12.6 mmHg after 40 to 42 weeks in participants receiving tirzepatide, mostly attributed to weight loss.


Louis Aronne, MD, an endocrinologist, director of the Comprehensive Weight Control Center at Weill Cornell Medicine in New York City, and coauthor of the New England Journal of Medicine study on tirzepatide for obesity treatment, describes the Mounjaro results as “spectacular,” and for those in the highest weight categories, comparable with bariatric surgery results. “It's really quite a remarkable finding.”

Have GLP-1 and GIP Receptor Agonists Been Studied in BIPOC?

The effects of tirzepatide for type 2 diabetes control have been studied in detail in some members of Black, Indigenous, and People of Color (BIPOC) communities. For example, it shows promise for people in East Asian and Hispanic/Latino populations, Dr. Aronne says.

Results of the SURPASS-J trials in Japanese populations and analyses of data from Hispanic/Latino SURPASS-2 trial participants are examples. “Those are two areas we can address, and the answer is, it works just as well,” Aronne says.

Noting that Asian people tend to have lower BMIs — as well as lower BMI thresholds for obesity, as reported by the World Health Organization — he adds that tirzepatide “seems to be as effective and produced equivalent reductions in glucose in the SURPASS trials. But more work needs to be done to ensure that these outcomes are just as good in other ethnic groups.”

What Are the Possible Side Effects of Tirzepatide?

One-third of participants in the SURMOUNT-1 trial experienced nausea at some point, though it was typically mild and decreased over time.

The most common side effects of tirzepatide are gastrointestinal. In addition to nausea, they include:

  • Constipation
  • Diarrhea
  • Decreased appetite
  • Indigestion
  • Stomach pain
  • Vomiting
In the SURMOUNT trial, gallbladder inflammation happened more often in those who took tirzepatide than in those in the placebo group, although the incidence was well under 1 percent.

Tirzepatide comes with a safety warning that it may cause tumors in the thyroid, including thyroid cancer, according to Lilly's patient information webpage for the drug.

“Mounjaro shouldn't be used in patients with, or who have a family history of, certain types of thyroid cancer such as medullary thyroid carcinoma, or in patients with multiple endocrine neoplasia type 2 (a genetic disorder of the endocrine glands),” says Florence Comite, MD, an endocrinologist who is the founder of the Comite Center for Precision Medicine and Healthy Longevity in New York City. “It also hasn't been studied in patients with type 1 diabetes on insulin.”

The FDA has identified intestinal blockage as a potential safety issue for all drugs targeting GLP-1 receptors, including tirzepatide, but also the others that are listed at the beginning of this article. Inclusion on the list does not mean that it has been proven that the drugs cause the health risk in question.


Do GLP-1 and GIP Receptor Agonists Interact Negatively With Other Drugs?

According to the FDA-listed drug label information for Mounjaro, it has the potential to affect the absorption of other medications because it delays gastric emptying. Be sure to check with your healthcare provider before taking Mounjaro and describe all the medications you are taking. This will help you avoid any possible medication interactions.

Are There Any Diet and Lifestyle Changes You Should Make with GLP-1 and GIP Receptor Agonists?

In short, yes. Put differently, tirzepatide doesn’t give you license to ditch a balanced diet and healthy lifestyle.

“These medications are less likely to work without changes to underlying habits and lifestyle,” says Jessica Cutler, MD, a bariatric surgeon at Mercy Medical Center in Baltimore. “I believe that without those changes, weight regain is very likely if the medication is stopped. That said, some of the effects of the medication, like earlier satiety and decreased cravings, may make it easier to commit to some of these other [lifestyle] changes. So far, that is what I have observed in most of my patients who are taking Mounjaro.”

Participants in the initial trial of tirzepatide for weight loss (SURMOUNT-1) ate a diet with a deficit of 500 calories per day, and did at least 150 minutes of physical activity each week, so research also suggests the drug — as effective as it may be for some people — is not a silver bullet for weight loss.

FAQ

How does tirzepatide work?
It mimics the actions of two hormones, GLP-1 and GIP, which work together to stimulate insulin secretion and slow stomach emptying after a meal, signal to the brain that you feel full, and regulate fat cells. All this helps regulate blood sugar levels and cause weight loss.
Research in people who are overweight or have obesity showed that it can be beneficial for them. One study found that tirzepatide injections, along with diet and exercise, helped people with a BMI of at least 27 (who did not have diabetes) lose an average of 22.5 percent of their body weight.
According to Mounjaro’s manufacturer, the most common ones are nausea and other gastrointestinal symptoms. The drug also has a safety warning that it may increase the risk of medullary thyroid cancer, so it shouldn’t be used by people at risk of this condition.
Mounjaro comes with a safety warning that it may cause thyroid tumors, including medullary thyroid cancer. It should not be taken by people with a personal or family history of a type of thyroid cancer called medullary thyroid carcinoma.

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