Is Mounjaro (tirzepatide) recommended for type 1 diabetics?

Mounjaro (Tirzepatide) is Not Recommended for Type 1 Diabetes

Mounjaro (tirzepatide) is not indicated for use in patients with type 1 diabetes mellitus and should not be used in this population. 1

FDA Labeling and Guideline Recommendations

The FDA label for Mounjaro (tirzepatide) explicitly states that it is:

• Indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus
• Not indicated for use in patients with type 1 diabetes mellitus 1

Current diabetes management guidelines from the American Diabetes Association (ADA) reinforce that insulin replacement therapy remains the cornerstone of type 1 diabetes treatment 2, 3. While adjunctive non-insulin therapies have been studied in type 1 diabetes, only pramlintide is currently FDA-approved for this purpose 2.

Evidence for Non-Insulin Therapies in Type 1 Diabetes

Approved Adjunctive Therapies

• Pramlintide: The only FDA-approved non-insulin medication for type 1 diabetes
  • Modest A1C reductions (0.3-0.4%)
  • Modest weight loss (1-2 kg) 2

GLP-1 Receptor Agonists in Type 1 Diabetes

• Liraglutide: Studied at 1.8 mg daily with modest results:
  • A1C reductions of approximately 0.2-0.4%
  • Weight loss of approximately 3-5 kg 2
• Semaglutide: Currently being studied prospectively in type 1 diabetes 2

Tirzepatide in Type 1 Diabetes

While a recent small observational study showed potential benefits of tirzepatide in type 1 diabetes (HbA1c reduction of 0.59% and weight loss of 10.1% at 8 months) 4, this represents preliminary data only. The study was:

• Small (26 patients)
• Observational in design
• Not FDA-approved for this indication
• Lacking long-term safety data in type 1 diabetes

Safety Concerns with Non-Insulin Therapies in Type 1 Diabetes

The use of certain non-insulin therapies in type 1 diabetes carries significant risks:

• SGLT2 inhibitors: Associated with a two- to four-fold increased risk of diabetic ketoacidosis (DKA) in type 1 diabetes 2
• GLP-1 RAs and dual GIP/GLP-1 RAs: Safety profile not fully established in type 1 diabetes; potential concerns include:
  • Delayed gastric emptying affecting insulin timing
  • Risk of hypoglycemia if insulin doses not appropriately adjusted
  • Potential gastrointestinal side effects 2, 5

Current Treatment Algorithm for Type 1 Diabetes

1. Insulin replacement therapy: The foundation of type 1 diabetes management

   • Multiple daily injections or continuous subcutaneous insulin infusion (insulin pump) 3
   • Insulin doses matched to carbohydrate intake, pre-meal glucose levels, and anticipated activity 3

2. Approved adjunctive therapy:

   • Pramlintide: May be considered for adults with type 1 diabetes 2

3. Investigational approaches:

   • Pancreas or islet cell transplantation: Reserved for specific situations such as:
     • Patients undergoing simultaneous renal transplantation
     • Following renal transplantation
     • Those with recurrent ketoacidosis or severe hypoglycemia despite intensive management 2

Conclusion

While research into adjunctive therapies for type 1 diabetes continues, including preliminary studies with tirzepatide 5, 4, current evidence and FDA labeling do not support the use of Mounjaro (tirzepatide) in patients with type 1 diabetes. Insulin replacement therapy remains the cornerstone of treatment, with pramlintide as the only FDA-approved adjunctive therapy.