Sorohan BM, et al. - Among adult Romanian patients with autosomal dominant polycystic kidney disease (ADPKD), chronic kidney disease (CKD) stages 1–5 not on dialysis and without diabetes mellitus, researchers assessed kidney function and body mass index (BMI) in relation to metformin treatment in this prospective, preliminary, single-arm study. The follow-up period at 24 months was completed by 16 out of 34 patients. The occurrence of adverse events was reported in 18 patients, and 63.6% of these events were gastrointestinal related. The most common adverse event (17.6%) was nausea. In intention-to-treat and in per-protocol population, mean estimated glomerular filtration rate (eGFR) altered by − 1.57 mL/min/1.73m² and by − 4.57 mL/min/1.73m², respectively, and mean BMI change was − 1.10 kg/m² and − 0.80 kg/m², respectively. Overall, findings revealed good tolerability of metformin, as well as its good safety profile even in ADPKD patients with advanced CKD. No link was found between metformin and change in eGFR or BMI across the follow-up period.