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BOSTON, MA – The landscape of treating type 2 diabetes and obesity is undergoing a dramatic transformation, with newer medications like tirzepatide rapidly overtaking established therapies, according to new research published in the Annals of Internal Medicine.
A study led by researchers at Mass General Brigham analyzed insurance claims from nearly two million commercially insured individuals in the U.S. between January 2021 and December 2023. The findings reveal a significant surge in the prescribing of GLP-1 receptor agonist (GLP-1RA) based medications, particularly tirzepatide (marketed as Mounjaro for diabetes and Zepbound for weight loss), coinciding with a decline in the initiation of older treatments such as metformin, sulfonylureas, and insulin.
“These findings highlight the rapidly shifting landscape of prescribing patterns for glucose-lowering and weight-lowering medications,” stated lead author Dr. John W. Ostrominski of Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system. He attributed the trends to “the combination of new evidence, increased awareness and prioritization of obesity treatment, and changing guidance for how to help patients manage these conditions.”
The data paints a striking picture of this shift:
- Weight Loss: In January 2021, about half of new weight-loss medication prescriptions for people without diabetes were for GLP-1RAs like semaglutide and tirzepatide. By December 2023, this figure soared to nearly 90%. Tirzepatide alone accounted for 31% of these new starts by the end of the period, while older weight loss drugs like phentermine and liraglutide saw decreased use.
- Type 2 Diabetes: Among patients with type 2 diabetes, the initiation rate for GLP-1RA-based medications climbed from 13% in January 2021 to 35% by December 2023. Conversely, metformin, the most commonly started diabetes drug in early 2021 (30% of starts), dropped to 19% by the end of 2023.
Researchers noted that tirzepatide’s uptake following its regulatory approval was particularly steep and sustained compared to other recently approved drugs for diabetes or obesity.
“We saw a sharp uptake of tirzepatide after regulatory approval—these kinds of trends are important for patients, clinicians, researchers, and policymakers to be aware of,” Dr. Ostrominski commented. He emphasized the need for clinicians to gain familiarity with these newer drugs, for researchers to investigate their long-term effects, and for health policies that ensure continued access and affordability.
While preliminary data is encouraging, the authors acknowledge that long-term outcomes trial data for tirzepatide, comparable to what exists for other GLP-1RAs like semaglutide, is not yet available. “In the future, data comparing the benefits of tirzepatide versus semaglutide for glycemic control, obesity management, and cardiovascular outcomes will help us have more informed conversations with patients about choosing the medication that’s right for them,” Dr. Ostrominski added.
The study, funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), has limitations, including its focus on commercially insured adults in the U.S., which may not fully represent other populations or healthcare systems.
The full study, “Trends in Utilization of Glucose- and Weight-Lowering Medications After Tirzepatide Approval in the United States,” was published on April 14, 2025, in the Annals of Internal Medicine (DOI: 10.7326/ANNALS-24-02870).
Disclaimer: This news article is based on findings from a published medical study and is intended for informational purposes only. It does not constitute medical advice. Readers should consult with a qualified healthcare professional for any health concerns or before making any decisions related to1 their health or treatment.
