From the Guidelines
Metformin dosing should start at 500 mg once or twice per day with meals, with a gradual increase to a maximum effective dose of up to 1,000 mg twice per day or 2,500 mg/day.
Key Considerations
- The initial dose can be 500 mg taken once or twice per day with meals, or 850 mg once per day 1.
- After 5-7 days, if gastrointestinal side effects have not occurred, the dose can be advanced to 850 mg or two 500 mg tablets, twice per day, taken before breakfast and/or dinner 1.
- The maximum effective dose can be up to 1,000 mg twice per day, but may be limited by gastrointestinal side effects, and modestly greater effectiveness has been observed with doses up to about 2,500 mg/day 1.
- A longer-acting formulation is available in some countries and can be given once per day, with a recommended dose of 500-2000 mg once daily, and a maximum daily dose of 2500 mg.
- It is essential to monitor glycemic control and adjust the dosage as needed, with preprandial and post-prandial levels checked to achieve target A1C levels 1.
From the FDA Drug Label
2 DOSAGE AND ADMINISTRATION
- 1 Adult Dosage Metformin Hydrochloride Tablets The recommended starting dose of metformin hydrochloride tablets are 500 mg orally twice a day or 850 mg once a day, given with meals. Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks on the basis of glycemic control and tolerability, up to a maximum dose of 2550 mg per day, given in divided doses. Doses above 2000 mg may be better tolerated given 3 times a day with meals.
- 2 Pediatric Dosage for metformin hydrochloride tablets The recommended starting dose of metformin hydrochloride tablets for pediatric patients 10 years of age and older is 500 mg orally twice a day, given with meals. Increase dosage in increments of 500 mg weekly on the basis of glycemic control and tolerability, up to a maximum of 2000 mg per day, given in divided doses twice daily.
The appropriate dosing for Metformin is as follows:
- Adults: Start with 500 mg orally twice a day or 850 mg once a day, given with meals. Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks, up to a maximum dose of 2550 mg per day.
- Pediatrics (10 years and older): Start with 500 mg orally twice a day, given with meals. Increase dosage in increments of 500 mg weekly, up to a maximum of 2000 mg per day. 2
From the Research
Metformin Dosing
The appropriate dosing for Metformin can vary depending on the specific formulation and patient population.
- The efficacy and safety of Metformin have been evaluated in several studies, including those using extended-release formulations 3, 4, 5 and delayed-release formulations 6.
- In general, the recommended dosing for Metformin is as follows:
- A study in Japanese patients with type 2 diabetes found that high-dose Metformin (up to 2250 mg/day) was effective and safe, with significant dose-dependent improvements in blood glucose control 7.
- The dosing frequency of Metformin may also impact its efficacy and safety, with some studies suggesting that once-daily dosing may be as effective as twice-daily dosing 4, 6.
Dose-Response Relationship
- Several studies have evaluated the dose-response relationship of Metformin, with results suggesting that:
- Higher doses of Metformin are associated with greater improvements in glycemic control, up to a certain point 3, 4, 7
- The efficacy of Metformin plateaus at higher doses, with minimal additional benefit beyond 1500-2000 mg/day 3, 4
- The safety and tolerability of Metformin are generally similar across different doses and formulations, although gastrointestinal side effects may be more common at higher doses 3, 4, 5, 6, 7