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A 32-Week Randomized Controlled Trial of Semaglutide versus Tirzepatide for Oxidative Stress and Weight Reduction in Patients with Obesity Without Diabetes

A 32-Week Randomized Controlled Trial of Semaglutide versus Tirzepatide for Oxidative Stress and Weight Reduction in Patients with Obesity Without Diabetes

ohara Makoto

Showa Medical University Hospital

1-5-8 Hatanodai, Shinagawa-ku

s6018@med.showa-u.ac.jp

Ohara Makoto

Showa Medical University Hospital

1-5-8 Hatanodai, Shinagawa-ku

+81-337848000

s6018@med.showa-u.ac.jp

Pending

June. 22, 2026

Interventional

randomized controlled trial

open(masking not used)

active control

parallel assignment

treatment purpose

Patients with obesity who are receiving outpatient care at the Department of Diabetes, Metabolism and Endocrinology, Showa Medical University Hospital and who meet all of the following criteria will be eligible for this study. The study population will consist of patients who meet the indication criteria for anti-obesity pharmacotherapy in Japan and who have not achieved sufficient weight reduction despite lifestyle intervention, including dietary and exercise therapy. For the purpose of this study, eligible patients will be limited to those with hypertension and/or dyslipidemia.
1)Age: Patients aged 20 years or older at the time of obtaining informed consent.
2)Degree of obesity: Patients who meet either of the following criteria:
a) BMI 27 kg/m2 or higher with two or more obesity-related health disorders, at least one of which is hypertension or dyslipidemia.
b) BMI 35 kg/m2 or higher with either hypertension or dyslipidemia.
3)Lifestyle intervention: Patients who, in accordance with the indication criteria for anti-obesity pharmacotherapy in Japan, have undergone lifestyle intervention, including dietary and exercise therapy, for at least 6 months but have not achieved sufficient weight reduction, and for whom the investigator judges pharmacotherapy to be indicated.
4)Informed consent: Patients who understand the contents of the study and provide written informed consent.

1)Patients with diabetes mellitus or those strongly suspected of having diabetes, defined as HbA1c 6.5% or higher, a history of diabetes, or current use of antidiabetic medication.
2)Patients diagnosed with secondary obesity.
3)Patients who are pregnant, breastfeeding, or planning pregnancy during the study period.
4)Patients with eGFR less than 30 mL/min/1.73m2.
5)Patients with severe hepatic impairment.
6)Patients with a history of pancreatitis, either acute or chronic, or those with findings suggestive of pancreatitis.
7)Patients with a history of medullary thyroid carcinoma, MTC, or a personal or family history of multiple endocrine neoplasia syndrome type 2, MEN2.
8)Patients with severe gastrointestinal disease, such as severe gastroparesis, conditions associated with a high risk of intestinal obstruction, or active inflammatory bowel disease, in whom the tolerability or safety of the study drug cannot be ensured.
9)Patients currently receiving treatment for gallbladder or biliary tract disease, or those with recurrent gallbladder or biliary tract disease who are judged by the treating physician to be at high risk.
10)Patients for whom initiation or modification of treatments expected to markedly affect body weight is planned during the study period, including new initiation or dose escalation of systemic corticosteroids, concomitant use of other anti-obesity drugs, or bariatric surgery.
11)Patients with a history of severe hypersensitivity to semaglutide, tirzepatide, or related agents, or those with any contraindication to these drugs.
12)Patients with malignant disease.
13)Patients judged to have difficulty participating in the study or adhering to treatment because of a severe psychiatric disorder or eating disorder.
14)Patients judged to be inappropriate for study participation for safety reasons, such as those immediately after a major cardiovascular event.
15)Patients judged unlikely to complete the 32 week follow-up, including clinic visits and assessments, such as those planning to relocate or expected to require long-term hospitalization.
16)Patients otherwise judged by the principal investigator or subinvestigator to be inappropriate for participation in the study for reasons including safety concerns, poor adherence, or difficulty in data collection.

Both

Non-diabetic obesity

Participants will be randomly assigned to either the semaglutide group or the tirzepatide group. In the semaglutide group, semaglutide will be initiated at 0.25 mg once weekly and escalated every 4 weeks up to 2.4 mg once weekly. In the tirzepatide group, tirzepatide will be initiated at 2.5 mg once weekly and increased to 5 mg once weekly after 4 weeks; thereafter, the dose may be escalated at intervals of at least 4 weeks, according to tolerability, up to a maximum of 15 mg once weekly.

Oxidative stress marker (d-ROMs) at Week 32

1. Body weight change rate at Week 32
2. Change in eating behavior questionnaire score exploratory

+81-3-3784-8129

May. 28, 2026

No

none