The latent autoimmune diabetes in adults (LADA) is a subgroup of type 1 diabetes, which procession of autoimmune destruction of beta-cells was slower than classic type 1 diabetes. To investigate the pathogenesis of LADA, we examined the lymphocyte subsets including the CD4(+)CD25(+) T-cells in 60 LADA patients and 30 patients of type 2 diabetes and 30 healthy individuals by FACS. And we compared the expression of FOXP3 mRNA in CD4(+) T-cell between 10 patients of LADA and 10 matched healthy individuals by real time PCR. The percent of CD4(+)CD25(+) T-cells were higher (11.89+/-4.96% versus 8.16+/-3.65%, P<0.01), and the percent CD8(+) T-cells elevated (24.58+/-6.80% versus 19.39+/-7.12, P<0.01) in LADA patients than healthy individuals. While the expression of FOXP3 mRNA in CD4(+) T-cell was markedly decreased in LADA patients (0.52-fold, n=10, P=0.004) compared with normal subjects. In addition, the percent of CD8(+) T-cells related with GAD-Ab titers in LADA patients (r=0.292, P=0.03). Our results showed that there were cellular immune disorder and decreased CD4(+) regulatory T-cells in LADA patients. The adoptive transfer regulatory T-cells seem to be a potential therapeutics for LADA.