Clinical comparison · GLP-1 & weight management · Updated 2026-07-02
Semaglutide is an injectable GLP-1 receptor agonist; metformin is an oral biguanide insulin sensitizer. This table reproduces FDA-labeled and trial-reported facts verbatim, per cell. The two are different drug classes studied for different primary endpoints, so their outcomes are not directly comparable. The page does not rank them.
Every value below is reproduced verbatim from an FDA prescribing-information document or a published clinical trial, and each cell links to its source. This page does not rank the two options, does not declare one safer or more effective, and is not medical advice.
| Dimension | Semaglutide | Metformin |
|---|---|---|
| Drug class | GLP-1 receptor agonist[1] | Biguanide (insulin sensitizer)[2] |
| Route | Once-weekly subcutaneous injection (or daily oral Rybelsus)[1] | Oral tablet (immediate- or extended-release)[2] |
| Most common GI adverse event | Nausea 15-20%[1] | Diarrhea 53.2% (monotherapy)[2] |
| Reported outcome | -14.9% mean body-weight change at week 68 vs -2.4% placebo (STEP 1)[3] | Improves ovulation and pregnancy rates vs placebo in PCOS (Cochrane)[4] |
| Serious labeled risk | Boxed warning: thyroid C-cell tumors (MTC/MEN 2 contraindication)[1] | Lactic acidosis (rare); risk rises with renal impairment[2] |
| Pregnancy | Not recommended; discontinue >=2 months before a planned pregnancy[5] | Sometimes continued under specialist care (historical category B)[2] |
Different endpoints, not comparable
STEP 1 measured percentage body-weight change for semaglutide; the Cochrane review of metformin in PCOS measured ovulation and pregnancy rates. Because the endpoints and populations differ, these results cannot be lined up as a head-to-head. Cochrane — Metformin for PCOS
No. Semaglutide is a GLP-1 receptor agonist (injectable), while metformin is an oral biguanide insulin sensitizer (FDA labels).
The FDA Glucophage label (historically category B) notes it is sometimes continued under specialist care, whereas semaglutide should be discontinued at least 2 months before a planned pregnancy.
Editorial reviews from ClearHormones of telehealth providers in this category. These are not treatment recommendations, and prescribing decisions rest with a licensed clinician.