Standard Starting Dosage for Adults
Metformin for type 2 diabetes in adults typically starts at 500 mg once or twice daily with meals to minimize gastrointestinal upset. Providers often increase this gradually over 1-2 weeks based on blood glucose response.[1][2]
Maximum Dosage and Titration
The usual maximum is 2,000-2,550 mg per day, split into 2-3 doses (e.g., 850 mg three times daily or 1,000 mg twice daily). Titration exceeds 2,000 mg/day only if needed and tolerated, with monitoring for lactic acidosis risk.[1][3]
Dosage Adjustments for Kidney Function
Reduce dose if eGFR falls below 60 mL/min/1.73 m². For eGFR 30-45, max 2,000 mg/day; 45-60, max 2,000 mg with caution. Stop if eGFR drops below 30.[2][4]
Use in Prediabetes or Weight Management
Off-label for prediabetes, start at 500 mg daily, titrate to 850 mg twice daily. For weight loss (e.g., PCOS), 1,500-2,500 mg/day divided doses, though not FDA-approved for this.[1][5]
Common Forms and Switching
Immediate-release tablets: 500, 850, 1,000 mg. Extended-release (e.g., Glucophage XR): start 500 mg once daily, max 2,000 mg. Switch from IR to ER at same total daily dose.[2][3]
Missed Dose or Overdose Risks
Take missed dose with next meal if soon after; skip if near next dose. Overdose (>5g) risks lactic acidosis—seek emergency care with symptoms like nausea, hypothermia.[1][4]
Sources
[1]: FDA Label - Glucophage (Metformin)
[2]: UpToDate - Metformin Dosing
[3]: Drugs.com - Metformin Dosage
[4]: American Diabetes Association Standards 2023
[5]: Mayo Clinic - Metformin Overview