Metformin
A decades-old, inexpensive diabetes medication with mild weight effects, often combined with GLP-1 therapy.
Metformin is the workhorse of type 2 diabetes: it reduces glucose production by the liver and improves insulin sensitivity, costs a few dollars a month, and has safety data stretching back to the 1950s. It is not an obesity drug — average weight effects are a modest 1–3 kg — but it resists the weight gain many older diabetes drugs cause.
In weight medicine it plays supporting roles: first-line therapy in prediabetes and PCOS, a frequent companion to GLP-1 medications in diabetic patients, and occasionally an off-label aid in antipsychotic-associated weight gain. Patients sometimes arrive expecting metformin to be a cheap Wegovy substitute; the honest framing is different tool, different job.
This glossary entry is general information, not medical advice, and is written to be consistent with FDA prescribing information and primary trial publications as of its last review. Always consult a licensed healthcare provider for personal medical decisions.
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