Endothelial-specific molecule 1 (endocan) is expressed by endothelial cells and may have a major role in the regulation of cell adhesion and in the pathogenesis of inflammatory disorders. We aimed to assess change in endocan levels after 3 months of lifestyle change recommendations and guideline-based treatment. Diabetic patients (n = 77) who had neither chronic kidney disease nor chronic inflammatory disease were included. After baseline evaluation, the patients were advised lifestyle changes, and their medical treatment was determined individually according to recommendations of the American Diabetes Association (ADA) guidelines. At the end of third month patients were reevaluated. Baseline endocan levels were significantly increased in the study group compared with the control group. The third-month laboratory workup showed significant reductions in hemoglobin A1c, urinary albumin-to-creatinine ratio (UACR), and endocan levels. Only δ-UACR was independently correlated with δ-endocan in multivariate linear regression analysis. Our findings suggest that serum endocan concentrations are elevated in patients with type 2 diabetes and decrease following anti-hyperglycemic treatment. Furthermore, decrease in endocan concentrations might be associated with improved glycemic control and reductions in UACR.