What is the metformin dose?

From the Guidelines

The metformin dose is typically started at 500 mg once or twice per day with meals and can be titrated up to a maximum effective dose of 2000 mg per day.

Metformin Dosing

• The initial dose of metformin is usually 500 mg taken once or twice per day with meals, which can help mitigate gastrointestinal side effects 1.
• The dose can be gradually increased every 5-7 days to minimize gastrointestinal intolerance, with a common maintenance dose of 850 mg twice per day 1.
• The maximum effective dose of metformin is up to 2000 mg per day, although doses up to 2550 mg per day have been used in some cases 1.

Important Considerations

• Metformin is contraindicated in patients with severe renal impairment (eGFR < 30 mL/min/1.73 m²) due to the risk of lactic acidosis 1.
• Patients with an eGFR of 30-45 mL/min/1.73 m² should be monitored closely for signs of lactic acidosis and may require dose adjustments 1.
• Metformin can cause vitamin B12 deficiency, and periodic testing of vitamin B12 levels is recommended, especially in patients with anemia or peripheral neuropathy 1.

From the FDA Drug Label

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. The metformin dose is:

• Starting dose: 500 mg orally twice a day or 850 mg once a day
• Maximum dose: 2550 mg per day, given in divided doses
• Dose increments: 500 mg weekly or 850 mg every 2 weeks 2

From the Research

Metformin Dose

The metformin dose varies depending on the patient's condition and the desired outcome.

• The typical dose of metformin for type 2 diabetes is 1000 mg twice daily 3.
• For patients with reduced kidney function, the dose should be adjusted to avoid lactic acidosis risk, with a maximum daily dose of 2250,1700,1250,1000, and 500 mg for patients with normal kidney function, CKD stage 2, 3a, 3b, and 4, respectively 4.
• In patients with polycystic ovary syndrome (PCOS), different doses of metformin (1000,1500, and 1700 mg) have been shown to have the same effects on clinical, biochemical, and metabolic parameters 5.
• For non-diabetic individuals with obesity, metformin up to a dosage of 2500 mg per day has been shown to be effective in reducing weight 6.
• Low doses of metformin (500 mg twice daily) have been used in the treatment of type II non-insulin-dependent diabetes, with significant improvements in glycemic control 7.

Factors Affecting Metformin Dose

The dose of metformin may be affected by several factors, including:

• Kidney function: patients with reduced kidney function require lower doses of metformin to avoid lactic acidosis risk 4.
• Insulin resistance: patients with severe insulin resistance may require higher doses of metformin to achieve significant weight loss 6.
• BMI: the degree of weight loss achieved with metformin is independent of BMI 6.

Clinical Considerations

When prescribing metformin, clinicians should consider the individual patient's needs and adjust the dose accordingly.

• The minimum effective dose of metformin should be used to minimize side effects and maximize efficacy 5.
• Patients should be monitored regularly for changes in kidney function, glycemic control, and weight, and the dose of metformin adjusted as needed 3, 4, 6, 7.