Inappropriate metformin prescribing in elderly type 2 diabetes mellitus (T2DM) patients

Metformin is the most commonly prescribed anti-diabetic medication. However, it is often used despite the presence of contraindications and in unlicensed indications. The main aim of this study was to evaluate the frequency of metformin use before hospitalization in spite of contraindications in patients with type 2 diabetes mellitus (T2DM) and to evaluate the prevalence of metformin - associated side effects.

558 hospitalized patients (mean age = 66.65 ± 12.73 years) with poorly controlled T2DM were enrolled. Detailed medical history including the duration of T2DM, duration of hypoglycemic agents usage prior to hospitalization and possible metformin-associated side effects was recorded. Patients were subjected to a thorough physical examination and indispensable biochemical and diagnostic research panel was performed to establish the degree of heart failure, sufficiency of the respiratory system and kidney function.

335 out of 558 patients were treated before hospitalization with metformin alone or in combination with other hypoglycemic agents, mostly sulfonylureas. Contraindications to metformin were found in 275 patients and despite this 120 of them were using this medication in an average dose of 1793.91 ± 701.61 mg. However, none of them reported any serious adverse effects and no significant pH changes were observed. Only three patients reported moderate dyspepsia.

The results of this study indicate a relatively good tolerability of metformin by patients with the traditional contraindications to this drug. These findings support other authors' suggestion that indications and contraindications to metformin should be re-evaluated.