Popular GLP-1 receptor agonist drugs (GLP-1 RAs) for weight loss appear to be similarly effective among patients of different ages, races, and starting weight, with women benefiting somewhat more than men, according to a study led by researchers at the Johns Hopkins Bloomberg School of Public Health.
The study examined 64 clinical trials involving semaglutide (Ozempic), dulaglutide (Trulicity), and other drugs in this class. The trials collectively included tens of thousands of patients. The analysis found that on average women who took GLP-1 RAs lost about 11% of their starting weight, compared to about 7% among men. By contrast, the analysis showed similar effectiveness of the agents based on individuals’ age (under 65 versus 65 and older), race, ethnicity, starting body mass index (a measure of obesity), and starting Hgb-A1c (average blood sugar levels over the past three months).
The findings appear online March 2 in JAMA Internal Medicine .
“These results should give clinicians and their patients more confidence that GLP-1-RAs work similarly well across different racial and ethnic populations, and different ages and weights, though they appear to have modestly greater effectiveness among women compared to men,” says study senior author Hemal Mehta , PhD, an associate professor in the Bloomberg School’s Department of Epidemiology.
The authors note that GLP-1 RAs may be more effective in women because of synergistic interactions with estrogen, differences in how women’s bodies process the drug, and women’s lower median body weight.
GLP-1, a hormone secreted by cells in the gut after a meal, suppresses appetite and stimulates the release of insulin from the pancreas, which triggers glucose uptake from the blood. GLP-1 itself is unsuitable as a drug due to a short half-life in the blood. Over the past two decades, researchers have developed long-acting compounds that mimic the hormone’s effects. These GLP-1 RAs are now routinely prescribed for treating obesity and type 2 diabetes, and for preventing heart attacks and strokes.
The analysis excluded tirzepatide (Zepbound) because, in addition to GLP-1, it mimics a hormone with similar effects called GIP.
Despite their broad health impacts, GLP-1 RAs drugs do not provide strong benefits for all patients. Researchers have wondered if this was related to factors such as patient age, race, or starting weight.
For their study, the researchers gathered data from published research studies on registered clinical trials that compared GLP-1 RAs for weight loss to placebo or to other drugs. Their analysis covered a total of 64 different trials from 41 published articles through mid-2024. For each subgroup, the researchers analyzed trials involving relevant patient groups. For instance, when analyzing how effectiveness varied with patient age, the researchers used data from seven trials covering 4,314 patients.
Their analysis of GLP-1 RA effectiveness by sex covered 19,906 patients in six trials. The researchers found an average weight loss of 10.88% of initial body weight for women, and 6.78% for men, a statistically significant difference.
For the other characteristics studied—age, race, ethnicity, initial body mass index, initial HbA1c level—the weight loss outcomes were similar across groups, suggesting that systematic and clinically significant differences between these groups are unlikely.
“The popularity and the cost of GLP-1 RAs are such that we need more studies like this to better understand the benefits of these products in clinical practice, especially for individuals that might be under-represented in clinical trials,” says study corresponding author G. Caleb Alexander , MD, a professor in the Bloomberg School’s Department of Epidemiology.
“ Heterogeneity of Treatment Effects of Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss Among Adults: A Systematic Review and Meta-Analysis ” was co-authored by G. Caleb Alexander, Xuya Xiao, Sophie Dilek, Sydney Lewis, Qilin Deng, Minji Kim, Dami Bolanle, Ian Saldanha and Hemalkumar Mehta.
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