Based on the UKPDS Study results published in 1998, metformin is recommended by international guidelines as the firstline treatment among oral antidiabetic drugs in patients with type 2 diabetes. These guidelines were based on the beneficial effect of the initial intensive treatment of obese diabetic patients with metformin with respect to cardiovascular morbidity and all-cause mortality. The recently published results of the Hyperinsulinemia: the Outcome of its Metabolic Effects (HOME) trial gave further proof about beneficial effect of metformin on cardiovascular disease in a later phase of type 2 diabetes. The average duration of the study was 4.3 years, and 390 diabetic patients treated with insulin were included. The patients were randomized to additional metformin treatment or to placebo. The diabetic patients treated with metformin had significantly better glycemic control along with lower daily dose of insulin required, as well as significantly lower body weight. Primary combined endpoint of the HOME study - the incidence of all macrovascular and microvascular outcomes - was not significantly reduced with metformin treatment. Metformin treatment though led to a significant relative risk reduction of all macrovascular outcomes by 40 %, which was a secondary endpoint of the present study. From the point of view of evidence-based medicine the HOME study confirmed the indication of additional metformin treatment in the later phases of type 2 diabetes, in which patients require insulin treatment to achieve optimal diabetes control.