GLP-1 medications such as Ozempic and Wegovy have transformed treatment for type 2 diabetes and obesity because many patients see substantial blood-sugar improvements and weight loss. New research in Genome Medicine, however, suggests that genetic differences help explain why these drugs do not work equally well for everyone.
The study identified variants in the enzyme peptidyl-glycine alpha-amidating monooxygenase (PAM), which activates several peptide hormones including GLP-1. Roughly 10% of people carry PAM variants that researchers describe as conferring partial ‘GLP-1 resistance.’ One variant in particular, p.S539W, was linked to higher circulating GLP-1 levels but a diminished biological response: despite elevated hormone concentrations, carriers needed more GLP-1 to achieve the same blood-glucose effect, consistent with reduced sensitivity.
Importantly, the study evaluated GLP-1’s action on glucose regulation, not weight loss, and it remains uncertain whether the same genetic effects occur at the higher GLP-1 doses used for obesity. That distinction matters before concluding that these variants blunt weight-loss responses. Investigators and clinicians caution that genetics likely explain only a portion of observed variability in treatment outcomes, and routine genetic testing for GLP-1 response is not yet recommended for general clinical use.
Many non-genetic factors also shape how well GLP-1 therapies work. Common contributors to suboptimal results include incomplete dosing, stopping treatment early because of gastrointestinal side effects, insufficient duration of therapy, and competing metabolic or lifestyle conditions such as severe insulin resistance, disrupted sleep, sarcopenia, or concomitant medications that promote weight gain. Addressing these issues—optimizing dose and duration, managing side effects, and treating underlying medical problems—often improves responses.
When GLP-1 treatment is ineffective or only partly effective, clinicians and patients can consider several alternative or complementary approaches:
– Metabolic or bariatric surgery: Procedures such as sleeve gastrectomy and Roux-en-Y gastric bypass produce substantial and durable weight loss (average 25–35%) and improve metabolic health. Surgery also alters incretin signaling and insulin sensitivity in ways that can complement pharmacotherapy. Many experts argue these operations should be considered alongside drug options rather than only as a last resort.
– Combination pharmacotherapy: Obesity involves multiple pathways—appetite, reward, gut-brain hormones, and energy expenditure—so combining agents that target different mechanisms can boost effectiveness. Pairing a GLP-1 agent with drugs such as phentermine, topiramate, or bupropion-naltrexone, or using newer multi-receptor drugs that engage more than one pathway, may help when monotherapy falls short.
– Alternative medications: For some patients, using different classes of weight-loss drugs or agents that act at multiple receptors—either instead of or alongside GLP-1s—can produce better results.
– Lifestyle and behavioral strategies: Diet and exercise remain foundational. Reducing refined carbohydrates and added sugars while emphasizing protein, vegetables, and overall caloric balance supports weight loss. Combining aerobic and resistance exercise helps burn calories and preserve muscle mass. Dietary patterns such as the Mediterranean, DASH, or MIND diets, along with attention to hydration and adequate protein intake, are useful for weight and cardiometabolic health.
This research contributes to a growing interest in precision medicine for obesity: identifying who is most likely to benefit from particular therapies and when to pursue alternatives. For now, experts recommend that clinicians first optimize GLP-1 use and address contributing medical or lifestyle factors when a patient has a poor response. If results remain inadequate, combination drugs, alternative agents, or bariatric surgery may be appropriate next steps. Further studies are needed to confirm whether PAM and other genetic variants alter weight-loss outcomes at higher therapeutic doses and to guide personalized treatment decisions.