By Dr. Asnat Raziel, specialist in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal
Mounjaro for type 2 diabetes: what you need to know
Today, Mounjaro for type 2 diabetes is a topic that concerns many patients. Mounjaro is a weekly injection whose active ingredient is tirzepatide. Regulators originally approved it to control blood sugar in adults with type 2 diabetes. In addition, it lowers weight significantly, and this matters a great deal to most patients.
In this article I explain how the drug works and what the large trials found. I also describe what we know about the heart, what the side effects are and who the treatment suits.
How Mounjaro works in the body
After a meal, the gut releases two hormones called incretins: GLP-1 and GIP. Both signal the pancreas to release insulin, but only when blood sugar is high. Therefore, the risk of low blood sugar (hypoglycemia) is low when patients take the drug on its own.
Most drugs in this family, such as Ozempic, mimic only GLP-1. In contrast, tirzepatide activates both receptors at once. As a result, it slows stomach emptying, increases fullness and reduces the release of glucagon, a hormone that raises blood sugar. Many patients also report less food noise, meaning constant thoughts about food.
Mounjaro for type 2 diabetes: what the SURPASS trials found
The tirzepatide research program in diabetes goes by the name SURPASS. Its most notable trial compared the drug directly with semaglutide, the active ingredient in Ozempic.
Head-to-head with Ozempic
The SURPASS-2 trial enrolled 1,879 patients who were already taking metformin. The results published in NEJM show that after 40 weeks, glycated hemoglobin fell by 2.01, 2.24 and 2.30 percentage points at 5, 10 and 15 mg. In the semaglutide 1 mg group, the drop was 1.86 percentage points. Glycated hemoglobin (HbA1c) reflects average blood sugar over the past three months.
Weight also differed. Weight loss with tirzepatide was 1.9 to 5.5 kg greater than with semaglutide, depending on the dose. You will find a detailed comparison in my article on Mounjaro versus Wegovy, and in my review of Wegovy in diabetes treatment.
Weight loss in people with diabetes
The SURMOUNT-2 trial studied 938 adults with obesity and type 2 diabetes. After 72 weeks, they lost 12.8% of their weight on average at 10 mg, and 14.7% at 15 mg. In the placebo group, weight fell by 3.2%. In other words, even when diabetes makes weight loss harder, the drug works well.
Mounjaro for type 2 diabetes and the heart
Heart disease is the leading cause of death among people with diabetes. So the key question is whether the drug also protects the heart. The SURPASS-CVOT trial included 13,299 patients with type 2 diabetes and heart or blood vessel disease. The researchers compared tirzepatide with dulaglutide (Trulicity), a drug with proven heart protection.
Over about four years of follow-up, a major cardiac event (cardiac death, heart attack or stroke) occurred in 12.2% of the tirzepatide group and 13.1% of the dulaglutide group. Statistically, tirzepatide was not inferior to the established drug, but the trial did not prove it superior either. Following the trial, the FDA approved Mounjaro in August 2026 to reduce the risk of cardiac events in high-risk adults with type 2 diabetes. You will find more in my article on Mounjaro and heart health.
How to start Mounjaro for type 2 diabetes
You inject Mounjaro once a week, under the skin, on a fixed day. Treatment starts at 2.5 mg and rises gradually, usually every four weeks, up to a dose of 5 to 15 mg. The gradual increase helps the body adjust and reduces nausea.
At the same time, it is important to eat a protein-rich diet and stay active, especially with strength training. Good sleep also affects blood sugar and appetite, as I wrote in my article on sleep and health. The drug is part of a broader plan, not a substitute for it.
Safety: what to know about Mounjaro for type 2 diabetes
The common side effects affect the digestive system. In SURPASS-2, nausea occurred in 17% to 22% of patients, diarrhea in 13% to 16% and vomiting in 6% to 10%. Most effects were mild to moderate, and they usually passed over time.
However, there are several things to know in advance:
- People who also take insulin or a sulfonylurea are at higher risk of low blood sugar, so the doctor may lower their dose.
- Do not use the drug if you have a personal or family history of medullary thyroid cancer or MEN2 syndrome.
- Severe, persistent abdominal pain requires an immediate visit to a doctor, because of concern about pancreatitis.
- The drug may reduce the effectiveness of birth control pills, especially at the start of treatment and after a dose increase.
You will find practical tips for coping in my article on the drug’s side effects.
Who should consider Mounjaro for type 2 diabetes?
Mounjaro suits mainly adults with type 2 diabetes whose blood sugar remains too high, especially when they also carry excess weight. However, it does not treat type 1 diabetes. In addition, it may also have a role in prediabetes, as I explained in a separate article on Mounjaro and prediabetes.
In Israel, eligibility depends on the health fund. For example, at Maccabi, eligibility in diabetes covers patients whose diabetes remains uncontrolled despite earlier treatment with a GLP-1 drug, such as Ozempic or Trulicity. It is worth checking with your health fund and reading my review of Mounjaro in the health funds. You will find the full range of options on my page about drug treatment for obesity and metabolic disease.
Bottom line on Mounjaro for type 2 diabetes
Treatment with Mounjaro for type 2 diabetes now rests on large trials. The drug lowers blood sugar and weight significantly, and in the heart trial it was not inferior to a drug that already protects the heart. However, it requires medical follow-up, gradual dose increases and lifestyle change. At our clinic, we build a personal plan for every patient. If you would like to know my approach, you can read more about me.
This article provides general information and is not personal medical advice. For any question about your treatment, please consult your doctor.
Questions and answers
Is Mounjaro suitable for type 1 diabetes?
No. Regulators approved the drug for type 2 diabetes only, and it does not replace insulin in type 1 diabetes.
When does blood sugar improve?
Improvement usually begins in the first weeks and grows stronger as the dose rises. Doctors assess the full effect with a glycated hemoglobin test after about three months.
Can I stop treatment once my blood sugar is under control?
Type 2 diabetes is a chronic disease. Therefore, stopping may bring blood sugar and weight back to their earlier levels. It is best to plan any change in treatment with your doctor.
What is the difference between Mounjaro and Ozempic?
Ozempic mimics one hormone, GLP-1. Mounjaro acts on two hormones, GLP-1 and GIP. In the head-to-head comparison, it lowered blood sugar and weight more.
References
Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes
Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes
Injections for the treatment of obesity and diabetes – Maccabi Healthcare Services (in Hebrew)
Eli Lilly funded the SURPASS-2, SURMOUNT-2 and SURPASS-CVOT trials.
