Medical uses
Metformin is used to lower the blood sugar in those with type 2 diabetes. It is also used as a second-line agent for infertility in those with polycystic ovary syndrome. Type 2 diabetes
The American Diabetes Association and the American College of Physicians both recommend metformin as a first-line agent to treat type 2 diabetes. It is as effective as repaglinide and more effective than all other oral diabetes mellitus type 2 drugs. Efficacy
Treatment guidelines for major professional associations, including the European Association for the Study of Diabetes, the European Society for Cardiology, and the American Diabetes Association, describe evidence for the cardiovascular benefits of metformin as equivocal. A 2020 Cochrane systematic review did not find enough evidence of reduction of cardiovascular mortality, non-fatal myocardial infarction or non-fatal stroke when comparing metformin monotherapy to other glucose-lowering drugs, behaviour change interventions, placebo or no intervention.The use of metformin reduces body weight in people with type 2 diabetes mellitus in contrast to sulfonylureas, which are associated with weight gain. Some evidence shows that metformin is associated with weight loss in obesity in the absence of diabetes. Metformin has a lower risk of hypoglycemia than the sulfonylureas, although hypoglycemia has uncommonly occurred during intense exercise, calorie deficit, or when used with other agents to lower blood glucose. Metformin modestly reduces low density lipoprotein and triglyceride levels. Polycystic ovarian syndrome
In those with polycystic ovarian syndrome (PCOS), tentative evidence shows that metformin use increases the rate of live births.
The FDA is also collaborating with international regulators to share testing results for metformin.In July 2020, Lupin Pharmaceuticals pulled all lots (batches) of metformin after discovering unacceptably high levels of NDMA in tested samples.In August 2020, Bayshore Pharmaceuticals recalled two lots of tablets. Research
Metformin has been studied for its effects on multiple other conditions, including:

Non-alcoholic fatty liver disease
Premature puberty
Cancer
Cardiovascular disease in people with diabetes
AgingWhile metformin may reduce body weight in persons with fragile X syndrome,  whether it improves neurological or psychiatric symptoms is uncertain. Metformin has been studied in vivo (C. elegans and crickets) for effects on aging. A 2017 review found that people with diabetes who were taking metformin had lower all-cause mortality. They also had reduced cancer and cardiovascular disease compared with those on other therapies. References
Further reading
External links

"Metformin". Drug Information Portal. U.S. National Library of Medicine. "Metformin hydrochloride". Drug Information Portal. U.S. National Library of Medicine.