Free insulin growth factor-I and vascular endothelial growth factor in the vitreous fluid of patients with proliferative diabetic retinopathy.
OBJECTIVE
To investigate the relationship between insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor (VEGF) in the vitreous fluid of diabetic patients with proliferative diabetic retinopathy (PDR).


METHODS
Observational case-control study.


METHODS
In a prospective study, 37 consecutive diabetic patients with PDR (14 type I and 23 type II diabetes mellitus) in whom a vitrectomy was performed were compared with 21 nondiabetic patients with other conditions requiring vitrectomy (control group). Free IGF-I and VEGF were measured by ELISA.


RESULTS
Vitreal levels of both free IGF-1 and VEGF were higher in diabetic patients with PDR than in control subjects (P <.01, and P <.0001, respectively). After adjusting for total intravitreous protein concentration, VEGF (ng/mg of proteins) remained significantly higher in diabetic patients with PDR than in the control group (P <.0001), whereas free IGF-I (ng/mg of proteins) was lower in diabetic patients than in control subjects (P <.0001). The vitreous concentrations of VEGF were higher in patients with active PDR than in patients with quiescent PDR (P <.005), whereas vitreous free IGF-I was not related to PDR activity. Finally, we did not observe a correlation between the vitreal levels of free IGF-I and VEGF.


CONCLUSIONS
We conclude that free IGF-I and VEGF are both increased, but not related, within the vitreous fluid of diabetic patients with PDR. In addition, our results support the current concept that VEGF is directly involved in the pathogenesis of PDR, whereas the precise role of free IGF-I remains to be established.
Simó
Rafael
R
Division of Endocrinology, Diabetes Research Unit, Hospital General Universitari Vall d'Hebron, Barcelona, Spain. rsimo@hg.vhebron.es
Lecube
Albert
A
Segura
Rosa M
RM
García Arumí
José
J
Hernández
Cristina
C
D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000378:metabolism*; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008222:Lymphokines / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015861:Retinal Neovascularization / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014821:Vitrectomy; D014822:Vitreous Body / Q000378:metabolism*
D016228:Endothelial Growth Factors; D005136:Eye Proteins; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D007334:Insulin-Like Growth Factor I