Metformin induces lactate production in peripheral blood mononuclear cells and platelets through specific mitochondrial complex I inhibition.

Metformin is a widely used antidiabetic drug associated with the rare side effect of lactic acidosis which has been proposed to be linked to drug-induced mitochondrial dysfunction. Using respirometry, the aim of this study was to evaluate mitochondrial toxicity of metformin to human blood cells in relation to that of phenformin, a biguanide analogue withdrawn in most countries due to a high incidence of lactic acidosis.