Aims: Metformin is the most widely used drug for the first-line treatment of type 2 diabetes mellitus (T2DM), but its use and schedule have been poorly investigated in elderly patients.
Methods: We conducted an observational, cross-sectional, multicentric study on metformin in T2DM outpatients older than 65 years who were taking the drug for at least 6 months and referred to Italian Endocrinology and Diabetology Services. The primary endpoint was daily metformin dose, and secondary endpoints were the correlations between metformin dose and age, comorbidities, and concomitant use of other drugs. The study was open to all members of AME (Associazione Medici Endocrinologi).
Results: Fifteen Italian centers recruited 751 consecutive participants (42.9% older than 75 years, 48.6% females). T2DM duration was 12.9 ± 9.7 years (longer than 10 years in 53.8%). Metformin had been used for 10.3 ± 6.8 years (longer than 10 years in 52.4%). Metformin dose was 1.6 ± 0.9 g/day (>1.5 g/day in 63.4%). As compared to the youngest, participants older than 75 years did not differ for metformin daily dose or number of administrations. Metformin dose was significantly directly correlated to eGFR, diabetes duration, and metformin treatment duration.
Conclusion: In this real-world study, the minimum daily effective dose of metformin was prescribed in more than half of older T2DM outpatients.
Keywords: Type 2 diabetes mellitus, metformin, dosage, HbA1c level, first-line treatment, anti-diabetic drug.