The SERS spectra were measured from normal and the diabetic serum.In the diabetic serum,the band of amide II shifted to 1 585 cm^-1 and the relative intensity increased 14%,while the relative intensity of 593 cm^-1 which belongs to amide Ⅵ reduced 33%.For the protein side chain,the band at 1 368 cm^-1 assigned to the “buried” tryptophan shifted to 1 365 cm^-1 of the “exposed” and the relative intensity reduced 59%. The relative intensity of 635 cm^-1 assigned to the gauche conformation of the C—S decrased 15% and the band at 725 cm^-1 increased 58%.These indicate that the structure of the protein changed in the diabetic serum.The relative intensity at 1 449 cm^-1 assigned to the lipids characteristic increased 58%.The relative intensity of the glucide characteristic at 1 331,1 099 and 740 cm^-1 increased 35%,100% and 62%,respectively.So it is indicated that the content of lipids,glucide and protein increased in diabetic.These results may offer a powerful experimental basis for diabetes diagnosis and biochemistry mechanism study.