Increased levels of Nε - Carboxy methyl lysine (Nε -CML) are associated with topographic alterations in retinal pigment epithelium: A preliminary study

• Published in: Journal of diabetes and its complications 2016-07, Vol.30 (5), p.868-872
• Main Authors: Mishra, Nibha, Saxena, Sandeep, Ruia, Surabhi, Prasad, Senthamizh, Singh, Vinita, Khanna, Vinay, Staffa, Robert, Gaspar, Ludovit, Kruzliak, Peter
• Format: Article
• Language: English
• Subjects: Advanced glycation end product; Diabetic retinopathy; Endocrinology & Metabolism; Nε- Carboxy methyl lysine; Retinal pigment epithelium; Spectral domain optical coherence tomography
• ISSN: 1056-8727; 1873-460X
• DOI: 10.1016/j.jdiacomp.2016.03.011

Abstract Purpose To evaluate the association of serum levels of Nε - Carboxy methyl lysine (Nε -CML), an advanced glycation end product with topographic alterations in retinal pigment epithelium (RPE) in diabetic retinopathy on spectral domain optical coherence tomography (SD-OCT). Method Consecutive cases of type 2 diabetes mellitus with no retinopathy (n = 20); non-proliferative diabetic retinopathy (n = 20); proliferative diabetic retinopathy (n = 20) and healthy controls (n = 20) between the ages of 40 and 65 years were included. RPE alterations were graded on segmentation map of SD-OCT: grade 0, No RPE alterations; grade 1, RPE alterations in up to two quadrants and grade 2, RPE alterations in more than two quadrants. Serum level of Nε -CML and glycated hemoglobin (HbA1c) was analyzed using the standard protocol. Statistical analysis was done. Results Significant increase in Nε -CML was observed with increased severity of diabetic retinopathy (F = 34.1; p < 0.0001). Fisher exact test revealed significant increase in grades of RPE alterations with increased severity of diabetic retinopathy (p < 0.001). Univariate ordinal regression analysis was done to calculate the risk of progression in grades of RPE alteration with individual changes in variables like duration of diabetes (odds ratio = 1.37; p = 0.001), HbA1c (odds ratio = 1.37; p = 0.002) and Nε-CML (odds ratio = 1.37; p < 0.0001). Multivariate ordinal regression analysis for predicting progression in grades of RPE alteration revealed Nε-CML to be an independent predictor of increase in grades of RPE alteration (adjusted odds ratio = 1.07; p < 0.01) when duration of diabetes and HbA1c were held constant. Conclusion Increase in serum levels of Nε - Carboxy methyl lysine is significantly associated with topographic alterations in RPE. Grades of RPE alteration increase significantly with increased severity of diabetic retinopathy.