The term ‘prediabetes’ refers to impaired fasting glucose and impaired glucose tolerance, defined as increased plasma glucose 2 h after an oral glucose tolerance test. People with this disorder have an increased risk of developing type 2 diabetes. According to the recommendations of Diabetes Poland, patients with prediabetes should be offered lifestyle modification and pharmacotherapy with the use of metformin for persons at high risk of diabetes. This drug reduces insulin resistance in liver and skeletal muscle. In the Diabetes Prevention Program metformin slowed down the progression of prediabetes to type 2 diabetes. Metformin has been in use for many years, it is cheap, safe, and does not cause hypoglycaemia.