Studies on the additional properties of metformin continue despite the long period of its use as an antihyperglycemic drug. Metformin is a member of the biguanide class of drugs and is successfully used for many years in type 2 diabetes mellitus patients with normal weight, overweight, and obesity both in monotherapy and in combination with other sugar-lowering drugs. It can be used as a drug for the management of T2DM due to its high sugar-lowering activity, low risk of hypoglycemia when used as monotherapy, neutral effect on weight with its further moderate reduction, good safety profile, and availability for most patients. A decreased peripheral insulin resistance under the influence of metformin leads to increased utilization of glucose in the liver, muscles and adipose tissue, which results in an antihyperglycemic effect and, as a consequence of this, improvement of the disease management, preventing or slowing down the development of late complications of type 2 diabetes mellitus. Metformin has a proven track record as a drug with many positive effects, which was confirmed in numerous studies in patients with various complications of diabetes mellitus and concomitant pathologies. The article presents data on the use of metformin in patients with type 2 diabetes mellitus for the purpose of preventing sarcopenic obesity and managing its symptoms. Metformin presents some features of interest in preventing the development and treatment of non-alcoholic fatty liver disease and polycystic ovary syndrome.