The recommended starting dosage of metformin is 500 mg twice daily. The maximum dosage for children age 10 to 16 is 2000 mg, and for adults age 17 and older is 2550 mg. Your dose should be increased only when necessary and should be increased slowly in order to avoid side effects.
The dosage of metformin (Glucophage®) or metformin ER (Glucophage XR®) your healthcare provider prescribes will vary depending on a number of factors, including:
- How well your diabetes is controlled
- Other medical conditions you may have
- Other medications you may currently be taking.
As is always the case, do not adjust your dosage unless your healthcare provider specifically tells you to do so.
For regular (not long-acting) metformin, the dosing varies with age, as follows:
- Age 10 to 16 -- The recommended starting dose is metformin 500 mg twice daily. The maximum dosing for people in this age group is metformin 2000 mg total per day, divided into two or three doses.
- Age 17 and over -- The recommended starting dose is metformin 500 mg twice daily or 850 mg once daily. The maximum dose for people in this age group is 2550 mg total daily, divided into two or three doses per day.
For the long-acting form, metformin ER, the starting dose is metformin ER 500 mg once daily, and the maximum dosing is metformin ER 2000 mg once daily (or metformin ER 1000 mg twice daily).
The recommended starting dosage of both metformin and metformin ER for people taking insulin is 500 mg once daily. The maximum total daily dose for people taking insulin is 2500 mg for metformin and 2000 mg for metformin ER. Usually, when adding metformin to insulin, you should continue with your normal insulin dose.