The authors determined interleukin-16 (IL-16) content in blood serum of patients distributed into three groups using an immunoenzymic method (ELISA). The first group consisted of patients with type 2 DM and metabolic syndrome (MS); the second group with type 2 DM and without MS, the third group - with MS and without T2DM. The control group consisted of normoglycemic subjects without MS signs who were distributed into two subgroups: 1) with excessive weight; 2) with normal weight. A significant increase in IL-16 concentration in blood serum was noted in patients with T2DM associated with MS (249,5+/-75,3 pg/ml) versus patients with MS without T2DM (130,5+/-41,2 pg/ml), and versus patients with T2DM without MS (69,5+/-35,6 pg/ml, P<0,05) and without obesity (77,4+/-11,6 pg/ml, P<0,05). This increase correlated with abdomen volume (r=0,4, P<0,05) and triglyceride level (r=0,4, P<0,05).