Metformin is one of the most commonly used hypoglycemic drugs in the treatment of diabetes, and its specific usage is very much related to the dosage form. The first is metformin regular tablets, because this dosage form is easy to cause gastrointestinal reaction, so it is generally recommended to take orally with or after meals, usually 1 tablet/times, 3 times/day, the total amount should not be more than 2000mg/day. The second type of dosage is metformin enteric-coated tablets, this type of dosage is relatively light on the gastrointestinal tract stimulation, can be taken orally before, during, or after meals, the maximum dose can not exceed 2,000mg/day, also 1 tablet/times, 3 times/day. The third is metformin extended-release tablets, this type of dosage form can be 1 tablet / time, morning or evening to eat a piece can be, the maximum amount of time is not more than 2000mg / day.