What metformin does
Metformin mainly reduces excess glucose release from the liver and improves the body's response to insulin. It is commonly used in type 2 diabetes and may be combined with other medicines when one treatment does not address all clinical goals.
Common problems and practical review
Nausea, loose stools, abdominal discomfort or reduced appetite can occur, particularly after starting or increasing treatment. Taking it as prescribed with food and using an appropriate formulation may help, but persistent symptoms need review rather than silent discontinuation.
Kidneys, illness and vitamin B12
Clinicians use kidney function to decide whether metformin remains appropriate. Vomiting, dehydration, severe infection, some procedures or contrast studies may require temporary instructions. Longer use can be associated with low vitamin B12, especially when anaemia or neuropathy symptoms are present.
Frequently asked questions
Does metformin damage the kidneys?
Metformin is not generally considered a cause of chronic kidney damage, but reduced kidney function can allow it to accumulate, so suitability and dose need review.
Can I stop metformin when my sugar improves?
Do not stop it solely because readings improved; improvement may mean the treatment is working. Review benefits, side effects and the overall plan with your clinician.
Guidelines and references
Dr. Pratyush Kumar · DNB Family Medicine, Sir Ganga Ram Hospital · DFID Diabetes Fellowship, Christian Medical College, Vellore
Updated and medically reviewed October 2026 · General education, not an individual prescription.