[en] ADMA (asymmetric dimethylarginine) is an endogenous competitive NOS (nitric oxide synthase) inhibitor. Elevation of ADMA level in body fluid is related to various diseases including diabetes mellitus, atherosclerosis, hypercholesterolemia, chronic heart failure, and hypertension. Our goal was to elucidate the role for ADMA and protein arginine methylation in the pathogenesis of diabetes and develop RI protein chip system for easy determination of ADMA levels in blood or tissues. As a result, ADMA regulated by protein arginine methylation, DDAH1, and NOS was demonstrated to play some role in the pathogenesis of diabetes mellitus, and arginine methylation of some proteins indicated their possible involvement in the change in ADMA levels. The concept of the RI protein chip system was devised such that firstly, ADMA was acylated by radio-labelled succinic acid, and followed by binding of the complex to anti-acyl ADMA-specific antibody coated on chip. Acylation condition of ADMA with radio-labelled succinic acid was established