correlation of plasma rbp4-to-vitamin a ratio with severity of diabetic retinopathy

Background & objective: diabetic retinopathy (dr) is a common microvascular complication of type 2 diabetes mellitus (t2dm) and the leading cause of vision loss in working-age adults. vitamin a (retinol) has a role in the mechanism of vision process and retinol binding protein-4 (rbp4), is a carrier of vitamin a, and as an adipokine may be associated with increased risk for insulin resistance and dr. this case-control study was aimed to determine and analyze plasma rbp4-to-vitamin a ratio in relation with terms of dr severity. materials & methods: in the present analytical cross-sectional study, 51 t2dm patients, aged 48-73 years old, were enrolled from those attending to the ophthalmology center of vali-e asr hospital, zanjan, iran. patients were categorized as non-retinopathy diabetic patients (nrdp) without any eye problem, those with mild non-proliferative dr (mild npdr) (n=12), those with severe non-proliferative diabetic retinopathy (severe npdr) (n=12), and those with proliferative dr (pdr) (n=12); a control group (n=15) was also considered. anthropometric parameters, bmi, and whr were determined and blood sample were taken from each participant after overnight fasting (12-14h) to measure their biochemical parameters. serum rbp4 and vitamin a levels were measured via elisa and c18 reverse-phase hplc methods, respectively. results: plasma rbp4 concentration was significantly higher in three different stages of dr than that of the control group suffering from diabetes (77.0±11.0, 81.7±10.9 and 88.3±11.9 vs. 71.4±12.3, respectively; p=0.004). the ratio of plasma rbp4-toretinol in dr groups was found to be significantly higher than that in the control group suffering from diabetes (0.21±0.06, 0.27±0.12 and 0.28±0.07 vs. 0.16±0.14, respectively; p=0.001). conclusion: higher plasma rbp4-to-vitamin a ratio was related to dr severity. further experimental studies with larger scales are recommended.