Research brief · 2026-09-09
Do GLP-1s Work Differently in Older Adults?
Semaglutide and tirzepatide are prescription medications, and the trials that led to their approval were general obesity and diabetes trials. They enrolled some adults over 65 along the way, and researchers have since gone back to ask whether that group responded differently. The short answer from those analyses is not much, but the analyses themselves have limits worth understanding.
The largest is a 2026 post hoc analysis by Alfaris and colleagues in Diabetes, Obesity and Metabolism, which pooled seven tirzepatide trials, including the SURMOUNT series and SUMMIT, and compared participants aged 65 and older with those under 65. Weight reduction and improvements in cardiometabolic risk factors and quality of life were described as broadly comparable between the age groups. On safety, the analysis found no clinically meaningful differences between tirzepatide and placebo in older adults across gastrointestinal tolerability, falls, fractures, depression outcomes, pancreatitis, and kidney, liver and gallbladder events.
A 2025 analysis by Rasouli and colleagues in Diabetes Therapy took a different slice: adults 65 and older with type 2 diabetes but a BMI under 30, pooled across the SURPASS trials, where weight was not the main lever. HbA1c fell by about two percentage points across doses. Weight loss was smaller than in the broader population. And older, non-obese participants were more likely to discontinue because of adverse events, even though the overall rate of adverse events was described as low.
None of those trials were designed around older adults; the age comparisons were made after the fact. A 2024 review by Žižka, Haluzík and Jude in Drugs and Aging stated that concise guidelines for older adults are not available and called for trials that track geriatric-specific outcomes: muscle mass, bone quality and physical function. A search of the trial registry finds a handful of dedicated studies, most still recruiting. Only two have completed, and the larger, a 2025 pilot by Dinkla and colleagues in Frontiers in Aging, enrolled 20 people with an average age of 72.7 for 20 weeks, finding meaningful weight loss and no significant change in bone density.
The limits matter most here because the stakes are highest here. Frail people, those over 80, and those with multiple conditions or cognitive impairment are largely absent from the pooled data. Grip strength, gait speed and fall risk were not primary outcomes in any of it. Why older adults stop more often, and whether that is manageable, is not resolved. For an older adult weighing one of these medications, the decision belongs with their physician, ideally one who knows their muscle, bone and function as well as their weight.
Sources
- Alfaris N, et al. Tirzepatide for Obesity in Adults ≥ 65 Years: A Post Hoc Analysis of the SURMOUNT and SUMMIT Clinical Trials
- Diabetes, Obesity & Metabolism 2026
- Rasouli N, et al. Tirzepatide for Older Adults with Type 2 Diabetes and Without Obesity: A Post Hoc Analysis of the SURPASS Clinical Trials
- Diabetes Therapy 2025
- Žižka O, Haluzík M, Jude EB. Pharmacological Treatment of Obesity in Older Adults
- Drugs & Aging 2024
- Dinkla L, et al. Bone mineral density and turnover response to GLP-1 receptor agonists in older adults: a 20-week pilot trial analysis
- Frontiers in Aging 2025
Peptide Proof reports what studies found. We do not give medical advice, dosing guidance, or treatment recommendations.