To study the effect of metformin on metabolic parameters, body weight (BW), and waist circumference (WC) in patients with abdominal obesity (AO).The results of using metformin 2000 mg daily for 3 months in 46 patients with AO. The comparison group consisted of 50 people. BW, WC, and blood pressure (BP) were measured; lipid profile parameters and blood insulin concentrations were determined; and Homeostasis Model Assessment (HOMA) estimates were calculated. Metabolic syndrome (MS) and AO were judged by the 2005 International Diabetes Federation (IDF) criteria.The study and comparison groups showed were reductions in BW by 4.2 and 1.7 kg and in WC by 4.2 and 1.1 cm, respectively. Metformin used in the patients with AO contributed to a more significant improvement in the lipid profile than in those who received no medication. A decrease in the HOMA index was observed only in the metformin group. The effects of the drug were more pronounced in MS and insulin resistance. The use of metformin in the patients with AO decreased lower BW and HOMA index and improved lipid metabolism even in the absence of MS.The trial has demonstrated that the people with AO may take metformin could be used in to reduce BW and WC and to treat and prevent MS.