Key Takeaway
The tirzepatide diabetes SURPASS trial program is one of the largest clinical research efforts ever conducted for a type 2 diabetes medication. Spanning five major trials and thousands of participants, the SURPASS data reshaped how clinicians think about blood sugar management and metabolic health.
The tirzepatide diabetes SURPASS trial program is one of the largest clinical research efforts ever conducted for a type 2 diabetes medication. Spanning five major trials and thousands of participants, the SURPASS data reshaped how clinicians think about blood sugar management and metabolic health. The results were striking enough that they changed treatment guidelines worldwide.
Key Takeaways: - Understand what the surpass trials measured - A1C Reductions: The Headline Numbers - Learn how tirzepatide compared to insulin - Cardiovascular and Weight Benefits
If you have type 2 diabetes or are at risk, this breakdown of the SURPASS trial results will help you understand what the research actually showed and what it could mean for you.
What the SURPASS Trials Measured
The SURPASS program included five phase 3 clinical trials, each designed to answer different questions about tirzepatide's effectiveness for type 2 diabetes.
SURPASS-1 tested tirzepatide as a standalone treatment (monotherapy) in people with type 2 diabetes who were not taking any other diabetes medications. Participants received tirzepatide at 5 mg, 10 mg, or 15 mg weekly doses, compared to placebo.
SURPASS-2 compared tirzepatide directly to semaglutide 1 mg (a GLP-1 receptor agonist) in people already taking metformin. This was a head-to-head comparison that drew significant attention.
SURPASS-3 compared tirzepatide to insulin degludec (a long-acting basal insulin) in people taking metformin with or without an SGLT2 inhibitor.
SURPASS-4 compared tirzepatide to insulin glargine in people with higher cardiovascular risk who were taking one to three oral diabetes medications.
SURPASS-5 tested tirzepatide as an add-on to insulin glargine in people who were not reaching their blood sugar targets with insulin alone.
"The key to successful GLP-1 therapy is setting realistic expectations and supporting patients through the titration phase. The side effects are manageable for most people, but they need to know what to expect.", Dr. Caroline Apovian, MD, Harvard Medical School
Across all five trials, the primary endpoint was change in A1C (hemoglobin A1C), the standard measure of average blood sugar over two to three months. Secondary endpoints included body weight change, fasting blood sugar, and the percentage of participants reaching target A1C levels.
A1C Reductions: The Headline Numbers
The A1C results from the SURPASS trials were remarkable by any standard in diabetes research. Here is what the data showed across dose levels.
SURPASS-1 (monotherapy vs. Placebo): - Tirzepatide 5 mg: A1C reduction of approximately 1.87% - Tirzepatide 10 mg: A1C reduction of approximately 1.89% - Tirzepatide 15 mg: A1C reduction of approximately 2.07% - Up to 88% of participants on the 15 mg dose achieved an A1C below 7%, the standard treatment target
SURPASS-2 (vs. Semaglutide 1 mg): - All three tirzepatide doses produced statistically superior A1C reductions compared to semaglutide 1 mg - Tirzepatide 15 mg reduced A1C by approximately 2.46%, compared to 1.86% for semaglutide 1 mg - A significant percentage of tirzepatide participants achieved A1C levels below 5.7%, which falls within the non-diabetic range
Patient Perspective: "What surprised me most was how much my blood sugar stabilized. I'm pre-diabetic, and my fasting glucose went from 118 to 92 in three months on tirzepatide.", Lisa T., 56, FormBlends patient (name changed for privacy)
SURPASS-3 (vs. Insulin degludec): - Tirzepatide at all doses produced greater A1C reductions than titrated insulin degludec - Participants on tirzepatide also lost weight, while those on insulin gained weight
These are clinical trial results from controlled settings. Individual results vary based on starting A1C, diet, exercise, other medications, and adherence to the prescribed protocol.
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How Tirzepatide Compared to Insulin
One of the most clinically significant findings from the SURPASS program was how tirzepatide performed against insulin, which has been the backbone of type 2 diabetes treatment for decades.
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Try the BMI Calculator →In SURPASS-3, tirzepatide outperformed insulin degludec on A1C reduction at all three doses. But the weight data told an even more compelling story. Participants on tirzepatide 15 mg lost an average of approximately 12 kg (about 26 pounds). Participants on insulin degludec gained an average of approximately 2.3 kg (about 5 pounds).
This weight difference matters enormously in diabetes management. Excess weight worsens insulin resistance, which is the core metabolic problem in type 2 diabetes. A medication that improves blood sugar while also reducing weight addresses both issues simultaneously. Insulin, while effective at lowering blood sugar, often leads to weight gain that can worsen the underlying metabolic condition over time.
In SURPASS-4, tirzepatide again outperformed insulin glargine in a population with higher cardiovascular risk. The A1C reductions were greater, weight loss was significant, and the cardiovascular safety profile was favorable.
This does not mean tirzepatide replaces insulin for everyone. Some people with type 2 diabetes, particularly those with very low insulin production, still need insulin therapy. But for many patients, the SURPASS data suggests tirzepatide may offer advantages that insulin cannot match.
For a detailed comparison of treatment options, read our .
Interested in exploring your options? who can evaluate whether tirzepatide may be appropriate for your diabetes management.
Cardiovascular and Weight Benefits
Beyond blood sugar control, the SURPASS trials revealed important secondary benefits that matter for long-term health.
Weight loss across all trials. Every SURPASS trial showed significant weight loss in tirzepatide groups. In SURPASS-2, participants on tirzepatide 15 mg lost approximately 12.4 kg compared to 6.2 kg for semaglutide 1 mg. Weight loss of this magnitude can independently improve insulin sensitivity, blood pressure, and cholesterol levels.
Cardiovascular markers. SURPASS-4 specifically enrolled participants with established cardiovascular disease or high cardiovascular risk. Tirzepatide demonstrated a favorable cardiovascular safety profile, with no increase in major cardiovascular events compared to insulin glargine. Additional cardiovascular outcome trial data continues to emerge.
Blood pressure improvements. Participants on tirzepatide across the trials showed reductions in systolic blood pressure, likely related to the weight loss and improved metabolic function.
Lipid improvements. Triglyceride levels decreased in tirzepatide groups. Some trials also showed modest improvements in LDL and HDL cholesterol levels.
These combined effects matter because type 2 diabetes is not just a blood sugar disease. It is a metabolic condition that increases risk for heart disease, stroke, and kidney disease. A treatment that addresses multiple cardiovascular risk factors simultaneously has advantages over one that only lowers blood sugar.
For more on the dual-agonist mechanism that drives these effects, see our article on . And if you are curious about whether you may qualify for GLP-1 treatment, you can .
Frequently Asked Questions
What is the SURPASS trial program?
SURPASS is a series of five phase 3 clinical trials that studied tirzepatide in people with type 2 diabetes. The trials compared tirzepatide to placebo, semaglutide, and different types of insulin across thousands of participants. The program demonstrated significant A1C reductions and weight loss across all tirzepatide dose levels.
How much did A1C drop in the SURPASS trials?
A1C reductions ranged from approximately 1.87% to 2.46% depending on the dose and trial. The highest dose (15 mg) consistently produced the greatest reductions. In SURPASS-2, up to 51% of participants on tirzepatide 15 mg achieved an A1C below 5.7%, which is within the non-diabetic range.
Is tirzepatide better than insulin for type 2 diabetes?
The SURPASS trials showed that tirzepatide produced greater A1C reductions than both insulin degludec and insulin glargine, while also causing significant weight loss instead of the weight gain typically seen with insulin. However, whether tirzepatide is better for a specific individual depends on their unique health situation. Some patients still require insulin therapy. A licensed provider can help determine the best approach for you.
Does tirzepatide have cardiovascular benefits?
The SURPASS trials showed that tirzepatide has a favorable cardiovascular safety profile. Participants experienced reductions in blood pressure, triglycerides, and body weight, all of which are cardiovascular risk factors. Dedicated cardiovascular outcome trial data provides further evidence. However, tirzepatide is not currently approved specifically as a cardiovascular medication.
Can I use tirzepatide if I am already on insulin?
SURPASS-5 studied tirzepatide as an add-on to insulin glargine and showed significant additional A1C reduction. Some providers may prescribe tirzepatide alongside insulin in certain cases. Others may transition patients from insulin to tirzepatide. This decision depends on your individual health profile and should be made with your provider.
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No two patients are the same, and your protocol shouldn't be either. FormBlends providers create customized treatment plans based on your health profile, goals, and preferences.
Sources & References
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. Doi:10.1056/NEJMoa2206038
- Garvey WT, Frias JP, Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2 (Garvey et al., Lancet, 2023)). Lancet. 2023;402(10402):613-626. Doi:10.1016/S0140-6736(23)01200-X
- Wadden TA, Chao AM, Engel S, et al. Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity (SURMOUNT-3 (Wadden et al., Nat Med, 2023)). Nat Med. 2023. Doi:10.1038/s41591-023-02597-w
- Aronne LJ, Sattar N, Horn DB, et al. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity (SURMOUNT-4 (Aronne et al., JAMA, 2024)). JAMA. 2024;331(1):38-48. Doi:10.1001/jama.2023.24945
- Malhotra A, Grunstein RR, Fietze I, et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity. N Engl J Med. 2024;391:1193-1205. Doi:10.1056/NEJMoa2404881
- Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384(11):989-1002. Doi:10.1056/NEJMoa2032183
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. Doi:10.1056/NEJMoa2206038
- Nauck MA, Meier JJ. Management of endocrine disease: Are all GLP-1 agonists equal in the treatment of type 2 diabetes? Eur J Endocrinol. 2019;181(6):R211-R234. Doi:10.1530/EJE-19-0566
- Stierman B, Afful J, Carroll MD, et al. National Health and Nutrition Examination Survey 2017-March 2020 Prepandemic Data Files. NCHS Data Brief. No. 492. CDC/NCHS. 2023.
- Sumithran P, Prendergast LA, Delbridge E, et al. Long-Term Persistence of Hormonal Adaptations to Weight Loss. N Engl J Med. 2011;365(17):1597-1604. Doi:10.1056/NEJMoa1105816
This article is for educational purposes only and does not constitute medical advice. Always consult with a licensed healthcare provider before starting, changing, or stopping any medication or supplement. FormBlends connects you with licensed providers who can evaluate your individual health needs.
Last updated: 2026-03-24