Background: Metabolic and haemodynamic factors concur in the development of diabetic nephropathy. Moreover, in diabetes, the presence of hypertension may accelerate the development of renal damage. Vascular endothelial growth factor (VEGF) stimulates microvascular permeability, endothelium-dependent vasodilation and angiogenesis and its synthesis is enhanced by hyperglycaemia, advanced glycation end-products (AGEs), tissue hypoxia and hypertension. VEGF appears to play a central role in mediating diabetic vasculopathy, and although VEGF and its receptors are expressed at renal level, its action in renal pathophysiology is unknown. The aim of this study was to elucidate whether presence and/or severity of renal dysfunction is related to circulating VEGF in patients with Type 2 diabetes and hypertension.
Design and methods: Fifty hypertensive Type 2 diabetic patients and 20 non-diabetic patients were included in the study. Renal function parameters such as albumin excretion rate (AER), and glomerular filtration rate (GFR), and VEGF plasma levels were analysed in all subjects, whereas %HbA1c and AGEs levels were evaluated in diabetic patients.
Results: GFR was significantly decreased in diabetic patients compared with the control subjects (74.36 +/- 15.95 vs 111.5 +/- 17.0 ml/min, p<0.0001). Three diabetic patients showed AER abnormalities (53.8 +/- 2.3 mg/24h). VEGF in diabetic patients was higher than in the control group (77.95 +/- 65.98 vs 49.30 +/- 40.8 pg/ml), but not significantly. %HbA1c and AGE levels were 6.6 +/- 1.5% and 11.59 +/- 8.09 UAGE/ml, respectively. No correlation was found between renal function, circulating VEGF levels and metabolic control.
Conclusion: Diabetes, in association with hypertension, significantly decreases renal function, but circulating VEGF may not reflect its concentration and action at renal level.