Levels of vascular endothelial growth factors (VEGF) are regulated in a complex network of adipokines, glucose control, and low grade inflammation together with activated platelets, leucocytes, and endothelial dysfunction. Increased levels of VEGF are associated with enhanced angiogenesis and impaired repair mechanisms of vascular lesions in endorgans. Little is known about the interaction of systemic VEGF levels with quality of diabetes control, biomarkers of inflammation, and diabetic nephropathy. Moreover, it is unclear, whether serum and plasma VEGF levels are similarly suited to reflect risk associated with VEGF.In this case control study, we analyzed these parameters in serum and plasma of age and sex matched controls without diabetes (n=99) and type 2 diabetes (n=302). Serum VEGF-A was significantly increased in patients with T2DM while plasma levels were in the same range as for controls. Individual levels varied in a wide range. Serum levels were 4.9 times higher in controls and 7.3 times higher in T2DM as compared to plasma levels. T2DM was associated with significantly higher levels of hsCRP, ALAT, and albumin/creatinine ratio. When calculated for tertiles of HbA1c, we observed a highly significant increase from tertile one to the upper tertile for serum VEGF-A but not for plasma VEGF-A. Correlation analysis revealed a significant relationship between VEGF-A, HbA1c, inflammation, and diabetic nephropathy. Our results indicate that increased VEGF-A levels in T2DM significantly depend on quality of HbA1c control. Serum levels of VEGF-A, with a strong contribution of platelet derived VEGF, better reflect the glycemic burden than plasma levels of VEGF-A. Mechanistic studies are needed to explore links to inflammation and diabetic nephropathy.
Increased levels of systemic vascular endothelial growth factors (VEGFs) in patients with diabetes are associated with increased risk of microvessel disease. On the other hand, low VEGF levels after intravitreal antibody application may be associated with acute cardiovascular complications and treatment failure. Individual levels of systemic VEGF vary in a wide range depending on analytical methods and quality of diabetes control. So far only limited information exists on intraindividual fluctuations over longer periods and circadian rhythms. We analysed the intraindividual variance of VEGF-A, VEGF-C and placental growth factor (PLGF) in CTAD (citrate-theophylline-adenine-dipyridamol) plasma as well as VEGF-A in serum over a period of 6 months in patients with stable controlled type 2 diabetes (10 M, 10 F) and age and sex matched subjects with normal glucose tolerance (NGT). Furthermore, circadian levels of VEGFs were controlled hourly from 7:30 a.m. to 7:30 p.m. under standardized metabolic ward conditions. In addition, the relationship to metabolic, hormonal and inflammatory biomarkers was analyzed. VEGF-A, VEGF-C and PLGF remained stable in plasma and VEGF-A in serum over 6 months in both groups. No circadian change was observed in VEGF-A serum and plasma concentrations. A minor decrease of VEGF-C plasma levels was evident after 5 p.m. in both groups and a significant peak of PLGF concentrations occurred after lunch, which was more pronounced in T2DM. In multivariate analysis, only serum VEGF-A correlated to diabetes duration, whereas VEGF-C only correlated to HbA1c and fasting blood glucose. We did not observe significant intraindividual variances for VEGF-A in serum and VEGF-A, VEGF-C and PLGF in CTAD plasma over a period of 6 months. Taken together, a single morning measurement of systemic VEGF levels after 7:30 am appears to be a reliable parameter for the individual risk associated with abnormal VEGF concentrations in blood.Trial Registration: NCT02325271
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