The exact mechanism of action of biguanides is not known. It is thought that biguanides inhibit the production and release of glucose by the liver and that they increase the sensitivity for insulin in peripheral tissues.
Metformin is the main representant of this group of drugs. The recommended dose for metformin is 500 mg 3 times a day.
I. Biguanide therapy brings no risk of hypoglycemia.
II. Normal kidney function is required for metformin therapy.
Extra info: Biguanides do not increase the concentration of insulin; they only increase the sensitivity for insulin. Biguanides are cleared by the kidneys. Renal insufficiency increases the circulatory levels of the drug and thus increases the risk for ketoacidosis.