Metformin (MF), a first-line drug to treat type 2 diabetes mellitus (T2DM), alone and in combination with other drugs, shows positive effect on steroidogenesis and spermatogenesis in men with T2DM and metabolic syndrome, thus MF treatment indicates prospective use for improvement of male reproductive functions and fertility in these disorders. The entry is focused on use of MF therapy for restoration of male reproductive functions in metabolic and endocrine disorders.