The degree of oxidized Cys34-HSA and the Cys-Cys34-HSA fraction of plasma samples obtained from 229 patients with chronic disease (including 139 patients with liver disease, 38 patients with kidney disease and 52 patients with diabetes mellitus) was determined by HPLC and ESI-TOFMS respectively and the correlation between these two parameters was examined. The gene discussed is ALB; the disease is diabetes mellitus.