Our aim was to compare serum vascular endothelial growth factor (VEGF) level in type 2 diabetes mellitus (T2DM) patients with comorbid OSA at screening and 6 month follow up visits. In the prospective cohort study following data were collected at screening visit: medical anamnesis; demographic and anthropometric data; Epworth sleepiness score data; laboratory (serum VEGF, complete blood count, biochemistry, immunology, complete urine test, including microalbuminuria) and instrumental investigation data (fundoscophy, laboratory polysomnography). At 6 months follow up visit we evaluated anthropometric data; Epworth sleepiness score; serum VEGF. Comparing VEGF level at screening and 6 month follow up visits showed significant decrease in VEGF level in both groups (P=0.0281 OSA+ and P=0.0278 OSA-). It was established direct correlation between decreased VEGF level and decreased HbA1c level (P=0.04696) and between decreased VEGF level and Epworth sleepiness score (P=0.0153) at 6 month follow up visit in OSA+ group. Our the study suggests that VEGF level decreases in parallel with diabetes compensation quality. Future researches are necessary to support this research.