Preadmission metformin use increased the incidence of hyperlactatemia at admission and 30-day in-hospital mortality among T2D patients with heart disease at high risk of hypoxia

Surprisingly, despite the high prevalence of metformin use in type 2 diabetes (T2D) patients with heart disease, limited safety data is available regarding metformin use in patients with acute and critical heart disease. In this single-center retrospective study, patients admitted to the cardiology department for heart failure (HF) or acute coronary syndrome (ACS) between December 2013 and December 2021 and who underwent arterial blood gas analysis at admission with an estimated glomerular clearance rate of ≥45 ml/min/1.73 m2 were identified. The incidences of hyperlactatemia, acidosis, and 30-day in-hospital mortality were compared between preadmission metformin users and nonusers. Of 526 admissions, 193/193 metformin users/nonusers were selected in a propensity score-matched model. Metformin users had greater lactate levels (2.55 ± 2.07 mmol/l vs. 2.00 ± 1.80 mmol/l P