There is a widely held belief among diabetics that metformin hurts and irritates the kidneys, discouraging many patients who should benefit from metformin use. In fact, metformin is recommended in many diabetes treatment guidelines around the world and is used as the first-line and lifelong treatment for patients with type 2 diabetes because of its glucose-lowering potency, general availability, low cost, weight loss, regulation of lipid metabolism, and cardiovascular protection, among other benefits. Metformin is stable in nature and is absorbed orally from the intestine and enters the bloodstream without binding to albumin, which is equivalent to traveling around the body and then excreting as a prototype through the kidneys. In a sense, metformin is excreted from the kidneys, just like water. The kidneys are only the organ that excretes metformin. It should be noted, however, that metformin should be avoided in cases of renal insufficiency because the excretion of metformin by the kidneys may be impaired, resulting in metformin accumulation and an increased risk of lactic acidosis.