Metformin is available in a variety of clinical dosage forms, different dosage forms are used differently, as follows: 1, ordinary tablets: in order to reduce the stimulation of the drug to the gastrointestinal tract, it should be taken at mealtime or immediately after meals.2, enteric-coated tablets or capsules: because enteric-coated preparations are slower in onset of action and the stimulation to the gastrointestinal tract is relatively mild, they can be taken before meals.3, slow-release preparations: it is only necessary to take once a day, and is recommended to take it at dinner. In addition, note that enteric and extended-release preparations should be swallowed whole, not broken, crushed or chewed, so as not to destroy the effect of enteric or extended-release.