Alterations in plasma insulin and C-peptide concentrations following hemodialysis were evaluated using five types of dialyzer, which made of polysulphone, polyethersulfone, cellulose triacetate, polymethylmethacrylate, and polyester-polymer alloy, in diabetic patients. Plasma insulin and C-peptide were cleared by hemodialysis; their clearance rates and reduction rates differed across dialyzer types.