Compare
Side by side.
| Semaglutide | Metformin | |
|---|---|---|
| Evidence | GRADE A | GRADE B |
| Category | GLP-1 | metabolic |
| Status | Rx | Rx |
| Typical cost | $200–$1,300 / mo | $5–$20 / mo |
| Mechanism | Mimics the gut hormone GLP-1: slows stomach emptying, reduces appetite and improves insulin release in response to food. | Lowers glucose production by the liver and improves insulin sensitivity. It mildly affects mitochondrial energy signaling (AMPK), which may mimic some effects of caloric restriction. |
| Human evidence | STEP trials showed ~15% average weight loss. SELECT showed a 20% reduction in major cardiovascular events in people with obesity and established heart disease. Kidney and other outcome data are accumulating. | Observational data suggest diabetics on metformin may have outcomes comparable to non-diabetics. The TAME trial is designed to test aging outcomes but has not reported. Some data suggest it can blunt exercise adaptations in older adults. |
| Side effects | Nausea, vomiting, constipation · Muscle loss with rapid weight loss · Gallbladder issues · Rare pancreatitis | GI upset, diarrhea · Vitamin B12 deficiency with long use · Rare lactic acidosis (kidney impairment) |
Not medical advice — talk to a licensed clinician. Content is educational, reflects published literature, and is not a recommendation to start, stop or change any treatment.