TY - JOUR
T1 - Diabetic retinopathy is associated with decreased serum levels of free IGF-I and changes of IGF-binding proteins
AU - Feldmann, Berit
AU - Jehle, Peter M.
AU - Mohan, Subburaman
AU - Lang, Gabriele E.
AU - Lang, Gerhard K.
AU - Brueckel, Joachim
AU - Boehm, Bernhard O.
N1 - Funding Information:
The authors wish to thank Dr A. Arnavaz, Mrs S. Ott and Mrs R. Herzog for their technical assistance and Mrs B. Füllgraf for statistical analysis. This work was supported by Landesforschungsschwerpunkte Baden-Wuerttemberg: “Wachstumsfaktor-Modulation als ther-apeutisches Prinzip” (PMJ), “Ursachen, Folgen und neue Therapieformen des Insulinmangels” (BOB), a NIH grant (AR31062; SM), a grant (“ZAKF Bausteinprojekt”) from the University of Ulm and a DFG grant (SFB) to BOB.
PY - 2000/2
Y1 - 2000/2
N2 - In patients with diabetic retinopathy, elevated serum levels of total circulating insulin-like growth factor-I (IGF-I) have been implicated as an important mediator of the disease. There is no study, however, measuring free IGF-I levels in patients with diabetic retinopathy which mediate the biological effects of IGF-I and are modulated by a complex system of six specific IGF binding proteins (IGFBPs) and several IGFBP proteases. To address the role of free IGF-I, we performed a cross-sectional study in 159 diabetes patients, among them 99 individuals with retinopathy (RP+; diabetes type 1/type 2: 41/58) and 60 without retinopathy (RP-; diabetes type 1/type 2: 22/38) and 110 age-matched healthy control subjects. Serum levels of both free and total IGF-I and IGFB-1 to -6 were determined by specific immunoassays. Free IGF-I levels were significantly lower in RP+ patients (1.1 ± 0.1 ng/ml) than in RP, patients (3.22 ± 0.3 ng/ml, P<0.005). In contrast, RP+ patients showed higher serum levels of total IGF-I (139.7 ± 5.8 ng/ml) than RP- patients (116.3 ± 8 ng/ml, P<0.05 vs RP+), which is consistent with previous reports. Type 1 diabetic patients with retinopathy showed significantly higher levels of IGFBP-1 but lower levels of IGFBP-2, -3 and -6 than type 1 patients without retinopathy. Type 2 patients with retinopathy showed lower levels of IGFBP-3 and -6, IGFBP-4 and -5 levels were not different between subgroups. Linear regression analysis revealed that free IGF-I levels correlated positively with IGFBP-3 and negatively with IGFBP-1. Furthermore, free IGF-I levels correlated negatively with HbA1c values, indicating that poor glycaemic control may contribute to a decreased IGF-I bioavailability. In summary, type 1 as well as type 2 diabetics with retinopathy showed markedly decreased levels of free IGF-I which correlated with complex alterations in IGFBPs and glycaemic control. (C) 2000 Harcourt Publishers Ltd.
AB - In patients with diabetic retinopathy, elevated serum levels of total circulating insulin-like growth factor-I (IGF-I) have been implicated as an important mediator of the disease. There is no study, however, measuring free IGF-I levels in patients with diabetic retinopathy which mediate the biological effects of IGF-I and are modulated by a complex system of six specific IGF binding proteins (IGFBPs) and several IGFBP proteases. To address the role of free IGF-I, we performed a cross-sectional study in 159 diabetes patients, among them 99 individuals with retinopathy (RP+; diabetes type 1/type 2: 41/58) and 60 without retinopathy (RP-; diabetes type 1/type 2: 22/38) and 110 age-matched healthy control subjects. Serum levels of both free and total IGF-I and IGFB-1 to -6 were determined by specific immunoassays. Free IGF-I levels were significantly lower in RP+ patients (1.1 ± 0.1 ng/ml) than in RP, patients (3.22 ± 0.3 ng/ml, P<0.005). In contrast, RP+ patients showed higher serum levels of total IGF-I (139.7 ± 5.8 ng/ml) than RP- patients (116.3 ± 8 ng/ml, P<0.05 vs RP+), which is consistent with previous reports. Type 1 diabetic patients with retinopathy showed significantly higher levels of IGFBP-1 but lower levels of IGFBP-2, -3 and -6 than type 1 patients without retinopathy. Type 2 patients with retinopathy showed lower levels of IGFBP-3 and -6, IGFBP-4 and -5 levels were not different between subgroups. Linear regression analysis revealed that free IGF-I levels correlated positively with IGFBP-3 and negatively with IGFBP-1. Furthermore, free IGF-I levels correlated negatively with HbA1c values, indicating that poor glycaemic control may contribute to a decreased IGF-I bioavailability. In summary, type 1 as well as type 2 diabetics with retinopathy showed markedly decreased levels of free IGF-I which correlated with complex alterations in IGFBPs and glycaemic control. (C) 2000 Harcourt Publishers Ltd.
KW - Diabetic retinopathy
KW - Insulin-like growth factor binding protein-1 to -6
KW - Insulin-like growth factor-I (IGF-I)
KW - Retinal regeneration
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U2 - 10.1054/ghir.2000.0140
DO - 10.1054/ghir.2000.0140
M3 - Article
C2 - 10753593
SN - 1096-6374
VL - 10
SP - 53
EP - 59
JO - Growth Hormone and IGF Research
JF - Growth Hormone and IGF Research
IS - 1
ER -