Hypoxic induction of vascular endothelial growth factor is markedly decreased in diabetic individuals who do not develop retinopathy

OBJECTIVE - A small percentage of patients do not develop any evidence of d iabetic retinopathy (DR) even after many years of diabetes. Vascular endoth elial growth factor (VEGF) has been implicated in the development of DR. Th erefore, we sought to determine if the regulation of VEGF differs in those patients who develop DR after many years of diabetes compared with those wh o do not develop DR. RESEARCH DESIGN AND METHODS - We performed standard 7-field stereoscopic fu ndus photography on 95 consecutive patients with type 1 and type 2 diabetes . Patients were categorized into 3 groups according to the presence or abse nce of DR and the duration of diabetes: group 1 was defined by presence of DR, group 2 was defined by absence of DR after >10 years duration of diabet es, and group 3 was defined by absence of DR with long-standing diabetes (g reater than or equal to 20 years for type 1 diabetes and greater than or eq ual to 15 years for type 2 diabetes). Monocytes from 40 mi peripheral blood were isolated from all patients, and the hypoxic induction of VEGF was det ermined in vitro. RESULTS - We found no significant difference in the basal level of VEGF in patients with and without DR. However, we did find a markedly significant d ifference in the hypoxic induction of VEGF between patients from group 1 an d group 3 (4.35 +/- 0.55 vs. 1.87 +/- 0.3, P < 0.00013). CONCLUSIONS - This study suggests that 1 mechanism for the absence of DR in patients with long-standing diabetes is a decreased hypoxic induction of V EGF.