Dr. Mersad Alimoradi 30 Sep 2022

Despite the wide range of available diabetes treatments, people with type 2 diabetes still struggle to achieve acceptable blood sugar levels.

Lilly’s new FDA-approved type 2 diabetes treatment, Mounjaro (tirzepatide), has the potential to change that.

Mounjaro is the first dual-action diabetes medicine that activates two kinds of hormone receptors, GIP and GLP-1, to improve blood sugar levels. 

Apart from lowering blood sugar levels, this novel type 2 diabetes drug may become the new weight loss medication for people with obesity.    

Continue reading to learn more about the new type 2 diabetes drug Mounjaro, how it works, how it’s different from other diabetes medications, and how it can aid weight loss in people with obesity.

What Is Mounjaro (Tirzepatide)?

Mounjaro, also known as tirzepatide, is a new injectable diabetes type 2 prescription medication by the American pharmaceutical company Eli Lilly and Company.

This new diabetes treatment is administered as an injection under the skin once a week. And the dosages are adjustable depending on the patient’s needs. 

In May 2022, the Food Drug Administration (FDA) approved the use of Lilly’s Mounjaro (tirzepatide) to control blood sugar (glucose) levels in adults with type 2 diabetes.     

Adults 18 years and older can use Mounjaro (tirzepatide) along with diet and exercise to manage hyperglycemia (high blood sugar). However, this drug is indicated only for people with type 2 diabetes and not type 1.     

Mounjaro is a first-of-its-kind in a new class of diabetes drugs; it’s the first and only FDA-approved diabetes medication that acts as a dual receptor agonist. That means it can target and activate the receptors of two hormones – the GIP (glucose-dependent insulinotropic polypeptide) and the GLP-1 (glucagon-like peptide-1) receptors.    

How Does Mounjaro Work?

Mounjaro diabetes medication works by improving blood sugar control. It stimulates insulin secretion, which then adjusts the blood sugar (glucose) levels.

The body produces the glucagon hormone to convert the stored glycogen into glucose, which raises your blood sugar levels.  After a meal, the body produces insulin that blocks the glucagon hormone to prevent spikes in blood sugar levels. 

GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) are two gut peptides known as incretin hormones. They can stimulate the secretion of insulin hormone when there are high glucose levels in the blood (hyperglycemia).  

Type 2 diabetes is a chronic condition in which the body cannot produce or use insulin properly, which causes high blood glucose levels. 

Mounjaro (tirzepatide) is a single dual-action molecule that can bind to and activate both GIP and GLP-1 receptors.

When injected under the skin, Mounjaro stimulates the secretion of the two incretin hormones, GIP and GLP-1. Those two hormones then cause the pancreas to release insulin. Consequently, insulin blocks the glucagon hormones and limits spikes in blood glucose after a meal. 

How Is Mounjaro Different Than Other Type 2 Diabetes Medications?

There’s a long list of available Type 2 diabetes drugs that work in different ways to lower blood sugar.

Glucagon-like peptide-1 (GLP-1) receptor agonists, such as Semaglutide (Ozempic), are a class of Type 2 diabetes medications. They can bind to and activate GLP-1 receptors to increase insulin production and decrease blood sugar levels.

So what sets Mounjaro (tirzepatide) apart from other Type 2 diabetes treatments? 

Mounjaro is the first and only GIP and GLP-1 receptor agonist – it can bind to and activate both the GIP and GLP-1 receptors. Therefore, it may be more effective in reducing blood sugar levels than other drugs.  

Clinical trials support that claim. Mounjaro was able to lower hemoglobin A1c levels (the average blood sugar level for the past two to three months) more than other diabetes medications.

That makes it potentially the most effective diabetes treatment so far.

How Can Mounjaro Help With Weight Loss?

Some of the side effects reported by patients treated with Mounjaro included a decreased appetite.

Mounjaro diabetes medication can slow down digestion. As a result, individuals feel full for a longer time and start eating less.

By reducing appetite and cravings, Mounjaro (tirzepatide) can aid weight loss in obese patients.

In the clinical studies, 85%-91% of participants who were obese lost more than 5% of their weight after 18 months of Mounjaro (tirzepatide) once-weekly injections. 

However, the trial did not compare the effectiveness of tirzepatide with other similar drugs, such as semaglutide and liraglutide. Further tests are needed to confirm whether tirzepatide is indeed the new best medication for obesity.

Clinical Evidence Supporting the New Diabetes Drug Mounjaro (Tirzepatide)

The SURPASS clinical trials investigated the long-term efficacy, safety, and side effects of tirzepatide as a treatment for people with type 2 diabetes mellitus. 

The phase 3 clinical studies included six global, two Japanese, and one Asia-Pacific studies. 

Mounjaro (tirzepatide) compared to semaglutide (Ozempic)

A phase-3 clinical trial assessed the efficacy and safety of tirzepatide (Mounjaro) compared to semaglutide (Ozempic), another GLP-1 receptor agonist.

A total of 1879 patients with type 2 diabetes received either tirzepatide or semaglutide treatments for ten months. 

The study concluded that tirzepatide was around 1% more effective at controlling blood sugar levels than semaglutide.

Tirzepatide (Mounjaro) also spurred more weight loss in type 2 diabetes patients than semaglutide (Ozempic).

Mounjaro (tirzepatide) compared to degludec insulin

The SURPASS-3 clinical trial compared the efficacy and safety of the new dual-action drug tirzepatide to that of a commonly used form of insulin called degludec.

1437 type 2 diabetes patients received either tirzepatide (Mounjaro) or degludec insulin treatments. 

After 13 months of treatment, tirzepatide (Mounjaro) was around 1% more effective than degludec in lowering hemoglobin A1c (HbA1c) levels (a measure of blood sugar control).

Moreover, patients lost around 7·5 kg to 12·9 kg (16.5 to 28.5 pounds) after receiving different doses of tirzepatide diabetes treatment. On the other hand, patients gained up to 2.3 kg after insulin degludec treatment.

Mounjaro (tirzepatide) compared to glargine insulin

During the SURPASS-4 clinical trials, researchers compared the novel dual GIP and GLP-1 receptor agonist tirzepatide to insulin glargine.  

1995 diabetes type 2 patients received at least one dose of Mounjaro or glargine insulin.

After 13 months of treatment, Mounjaro reduced hemoglobin A1c (HbA1c) by about 1% more than glargine insulin.

Furthermore, Mounjaro (tirzepatide) diabetes treatment did not increase the risk of cardiovascular disease.

In conclusion, researchers found Mounjaro (tirzepatide) more effective at managing blood sugar levels and inducing weight loss in type 2 diabetes patients than other common diabetes treatments.

Possible Side Effects of Mounjaro Type 2 Diabetes Drugs

According to the clinical trials, Mounjaro (tirzepatide) diabetes treatment was as safe as other GLP-1 receptor agonists.

The most common side effects of Mounjaro (tirzepatide) include:

  • Nausea
  • Vomiting
  • Diarrhea
  • Constipation
  • Decreased appetite
  • Abdominal discomfort or pain

Less common yet potentially severe adverse events include:

  • Hypersensitivity reactions
  • Gallstones
  • Cholecystitis (inflammation of the gallbladder)
  • Pancreatitis (inflammation of the pancreas)
  • Hypoglycemia/ low blood sugar (when used with insulin)

Mounjaro and other glucagon-like peptide-1 (GLP-1) receptor agonists can cause thyroid C-cell tumors in rats. However, it’s still not known whether Mounjaro causes thyroid tumors or medullary thyroid cancer in humans.

Therefore, patients with Multiple Endocrine Neoplasia syndrome type 2 or a family history of medullary thyroid cancer should not use Mounjaro (tirzepatide) medication.

Mounjaro (tirzepatide) may be the most effective type 2 diabetes and obesity treatment we have so far.  Although not yet FDA-approved for obesity, doctors may prescribe Mounjaro as an off-label weight loss medication and obesity treatment. 

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About the Author:
Dr. Mersad is a medical doctor, author, and editor based in Germany. He's managed to publish several research papers early in his career. He is passionate about spreading medical knowledge. Thus, he spends a big portion of his time writing educational articles for everyone to learn.