Objective: Omentin-1 is a circulating adipokine with anti-inflammatory, anti-atherosclerotic, cardioprotective effects. It is hypothesised that reduced levels of omentin-1 is connected with increase in arterial stiffness, thus leading to the rise in acute vascular events. A strong relationship between arterial stiffness and the levels of circulating omentin-1 in patients with diabetes mellitus type 2 (DM-2) and comorbid overweight or obesity was adapted from literature which necessitated for this study. Design and method: 98 patients with diabetes mellitus type 2 were examined, of which 64 patients (34 women and 30 men) with comorbid overweight or obesity (BMI more than 25), included in the 1st group, 34 patients with normal body weight (19 women and 1 5 men) were in the 2nd group at the Regional Hospital, Zaporizhzhia. As a control, 28 practically healthy individuals were examined, comparable with the 1st and 2nd groups by age and sex. The levels of circulating Omentin-1 was determined by enzyme-linked immunosorbent assay and arterial stiffness was assessed by the pulse wave velocity (PWV) of the elastic and muscular arteries during rheovasography. Results: Results: In patients of the 1st group, the level of omentin-1 was 127.5% lower than in the 2nd group, with a longer duration of diabetes, the average values of omentin-1 were lower by 39.2% (p < 0.05) in Group 1 and 25.9% (p < 0.05) in group 2 compared with the control group. PWV in muscular arteries in the 2nd group was 15.7% higher than in the 2nd and 34.3% than in the control; Differences in elastic arteries were 10.6% and 30.5%, respectively. A relationship was established between the level of omentin-1, as well as PWV in the muscular (r = -0.56, p < 0.05) and elastic arteries (r = -0.47, p < 0.05). Conclusions: In patients with DM-2 and comorbid overweight or obesity, a decrease in the level of omentin-1 was noted, which was associated with high arterial stiffness leading to an increased cardiovascular mortality risk. Thus, omentin-1 is a potential biomarker and a new combined therapeutic target for metabolic and vascular diseases.