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Metformin Use and Clinical Outcomes in Very Elderly Patients with Type 2 Diabetes and Chronic Kidney Disease

Marchini M

Medicina (Kaunas, Lithuania), 2026

624 participants

Abstract

Background and Objactives: Metformin is the most widely prescribed glucose-lowering therapy worldwide and is generally considered safe in patients with chronic kidney disease (CKD) with estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2. However, very elderly patients are underrepresented in pivotal trials, and evidence on metformin safety in this vulnerable population remains limited. We evaluated the association between metformin use and adverse clinical outcomes in very elderly patients with CKD and type 2 diabetes. Materials and Methods: We conducted a single-center retrospective observational study including 624 very elderly patients (age > 78 years) with CKD, type 2 diabetes mellitus, and eGFR > 30 mL/min/1.73 m2. Patients were stratified according to metformin exposure (309 metformin-treated and 315 controls). The primary composite outcome was the first occurrence of intensive care unit (ICU) admission, initiation of renal replacement therapy (RRT), lactic acidosis, or all-cause mortality. A propensity score-matched sensitivity analysis and hierarchical win ratio analysis were also performed to further address potential baseline confounding. Results: Over a median follow-up of 33.7 months, the primary composite outcome occurred more frequently in the metformin group than in controls (18.7% vs. 9.5%; HR 1.75; 95% CI 1.12-2.73; p = 0.013). Metformin use was associated with a higher risk of ICU admission (HR 2.33; 95% CI 1.33-4.08), RRT initiation (HR 1.90;…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 624 participants or records.

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