The proteomics analysis was used to search for the membrane proteins related to the type 2 diabetes in human red blood cell (RBC). To improve the solubilization and separation for membrane proteins during two-dimensional electrophoresis (2-DE), several types of chaotropes and surfactants were tested. The optimized condition was then screened. About 1000 protein spots from RBC membranes can be resolved on the 2-D gel. To compare the 2-DE patterns between RBC membranes of type 2 diabetic patients and healthy controls, a total of 42 proteins that were differentially expressed were found. The analysis shows that flotillin-1, a recently discovered membrane protein of RBC lipid rafts, appears to be affected in the disease. The result would be quite interesting because flotillin-1 in adipocytes functions is related to stimulate activation of glucose transporter 4 in response to insulin. Additionally, syntaxin 1C and arginase were also disregulated in patient RBC membranes. (C) 2003 Elsevier Inc. All rights reserved.