Does Ozempic work less well in Black people? My sister recently told me this, I wanted to explore what the science says. We're talking about GLP-1-based medicines, including Ozempic, Wegovy and Mounjaro. 1. What does the evidence show? Some real-world studies have found that Black patients lose less weight on these medicines than White patients. One study reported average weight loss of 4.9% compared with 7.1%. However, clinical trials haven't consistently found significant differences between racial groups. A difference in outcomes doesn't mean being Black is the biological cause. 2. Why does race complicate the picture? Race is a social classification, not a precise genetic category. The label "Black" includes people with enormously diverse genetic ancestries. Grouping everyone together can hide the biological, environmental and social factors responsible for differences in health. Race can identify inequalities without explaining their cause. 3. What does pharmacogenetics tell us? Pharmacogenetics examines how DNA variation influences our response to medicines. A 2026 Nature study involving almost 28,000 people taking GLP-1-based medicines identified a variant in the GLP1R gene, which encodes the receptor targeted by these drugs. People carrying this variant lost approximately 0.76 kg extra per copy. Researchers also identified variants associated with nausea and vomiting. 4. Does ancestry matter? Yes, but ancestry and race aren't interchangeable. The GLP1R variant associated with greater weight loss occurs at different frequencies across ancestral populations, approximately 40% in European ancestry populations compared with 7% in African ancestry populations. This could contribute to differences in drug response, but it doesn't mean everyone with African ancestry responds less well. A genetic association is not evidence that an entire racial group shares the same biology. 5. Genetics isn't the whole story. Treatment response also depends on medication type, dosage, other health conditions and access to treatment. Wider factors matter too: food availability, financial resources, where someone lives and experiences within healthcare. 6. So does race matter in healthcare? Absolutely, but not necessarily in the ways we assume. Race and racism can influence healthcare access, environmental exposures, socioeconomic opportunities and treatment by health professionals. And when genetic research disproportionately represents European ancestry populations, we risk developing medical knowledge that doesn't adequately represent everyone. The bigger question isn't whether Ozempic works differently because someone is Black. It's why individuals respond differently, and how genetics, ancestry, health, environment and structural inequalities interact. Race can reveal an inequality without explaining its cause. Pharmacogenetics should help us understand individuals, not reinforce racial assumptions. Scientific American, April 2026: https://www.scientificamerican.com/article/how-well-glp-1-weight-loss-drugs-work-may-depend-on-your-genetics/ Nature (2026): https://www.nature.com/articles/s41586-026-10330-z #Genetics #Ozempic #Mounjaro #Pharmacogenetics #RaceAndGenetics