The role of vascular endothelial growth factor in the progression of diabetic vascular complications.

PURPOSE: This study was planned to study the relationship between vascular endothelial growth factor (VEGF) as an angiogenic factor and different micro- and macrovascular complications in type II diabetic patients and look for a possible role of control on the serum level of VEGF.
METHODS: The study included 55 type II diabetic patients, 10 of them were not complicated with any of the vascular complications of type II diabetes mellitus (DM) (group 1), 21 patients had microvascular complication either retinopathy, nephropathy, or neuropathy (group 2), 14 patients had macrovascular complications either coronary artery disease or peripheral vascular disease (group 3), and 10 patients with mixed micro- and microvascular complications (group 4), as well as 15 healthy subjects served as control group. All subjects were subjected to complete clinical examination, including fundus examination, proper investigations with stress on electrocardiography, electromyography, nerve conduction velocity, Doppler study of the peripheral arteries, and laboratory investigations such as complete blood count, liver function test, serum creatinine, 24-h urinary albumin excretion, lipid profile, fasting and 2-h postprandial blood glucose, glycosylated haemoglobin (HbA(1c)), and serum VEGF.
RESULTS: The study revealed that there was a highly significant increase in the serum VEGF in the diabetic patients compared with the control group. The P-value (P<0.001) was detected and there was also a highly significant increase in the serum VEGF in the patients with different micro- and macrovascular diabetic complications compared with uncomplicated diabetic group (P<0.001). A highly significant increase in the serum VEGF in diabetic patients with proliferative diabetic retinopathy was detected compared with non-proliferative diabetic retinopathy (40.55±8.28 vs20.3±2.45, P<0.001) and in diabetic nephropathic patients with macroalbuminuria compared with those with microalbuminuria (36.14±6.99 vs19.42±2.44, P<0.001). The reduction of the serum VEGF in a group of diabetic patients with poor control when their diabetic state was corrected through 4 months follow-up was highly significant (17.29±1.61 before vs9.39±0.82 after control P<0.001), as well as the reduction of the serum VEGF, which was observed in a group of patients with proliferative diabetic retinopathy (PDR) when proper pan retinal photocoagulation (PRP) was applied to their retinae with 4 months follow-up (40.55±8.28 before vs21.15±1.76 after PRP, P<0.001). On the other hand, the impact of some clinical and laboratory parameters of our diabetic patients on the serum VEGF revealed significant positive correlations between serum VEGF and age of the patients, duration of diabetes, systolic and diastolic blood pressure, body mass index, fasting and 2-h postprandial blood glucose, HbA(1c), serum creatinine, degree of albuminuria and total cholesterol, LDL, and platelet count.
CONCLUSION: Serum VEGF was significantly increased in diabetic patients especially with micro- and macrovascular complications and the proper control of diabetes reduced the elevation of serum VEGF in uncontrolled diabetic patients, and in patients with PDR with proper PRP, indicating that VEGF is an angiogenic factor that reflects the degree of neovascularization in diabetic complications.