Objective To investigate changes in T lymphocyte subsets and NK cells in patients with simple Graves' disease(GD)and Graves' disease combined with type 2 diabetes mellitus(GD/T2DM).Methods Fifteen cases of GD/T2DM were selected from our hospital from November 2001 to November 2004.Before and after therapy thyroid function,thyroglobulin antibody(TGA),thyroid microsomal antibody(TMA)and blood glucose level were measured,and T lymphocyte subsets(CD3,CD4,CD8,CD4/CD8)and NK cells(CD56)were measured by immunofluorescence double labeling monoclonal antibody and flow cytometry,respectively.At the same time,comparison was made with simple GD(15 cases),T2DM(15 cases)and healthy control(20 cases).Results Before therapy,CD4/CD8,CD4 and NK cells in GD/T2DM were less than normal,and there was no significant difference in comparison with simple GD(P<0.05).In T2DM group,only CD4/CD8 and CD4 were less than those of healthy controls(P<0.05).When thyroid function recovered after 1 to 3 months of methimazole treatment in both GD/T2DM and simple GD groups,various indexes recovered,which were more obvious in simple GD.Conclusion Immune hypofunction of GD may be the key to the immune abnormality of GD/T2DM,which is more significant than that of simple GD or T2DM.The recovery of thyroid function and immune abnormality is not consistent,and the recovery of GD is more significant than that of GD/T2DM. Objective To investigate changes in T lymphocyte subsets and NK cells in patients with simple Graves 'disease (GD) and Graves' disease combined with type 2 diabetes mellitus (GD / T2DM). Fifteen cases of GD / T2DM were selected from our hospital from November 2001 to November 2004.Before and after therapy thyroid function, thyroglobulin antibody (TGA), thyroid microsomal antibody (TMA) and blood glucose level were measured, and T lymphocyte subsets (CD3, CD4, CD8, CD4 / CD8) and NK cells (CD56) were measured by immunofluorescence double labeling monoclonal antibody and flow cytometry, respectively. At the same time, comparison was made with simple GD (15 cases), T2DM (15 cases) and healthy control (20 cases). Results Before therapy, CD4 / CD8, CD4 and NK cells in GD / T2DM were less than normal, and there was no significant difference in comparison with simple GD (P <0.05) .In T2DM group, only CD4 / CD8 and CD4 were less than those of healthy controls (P <0.05) .When thyroid function recovered after 1 to 3 months of methimaz ole treatment in both GD / T2DM and simple GD groups, various indexes recovered, which were more obvious in simple GD. Conlusion Immune hypofunction of GD may be the key to the immune abnormality of GD / T2DM, which is more significant than that of simple GD or T2DM. The recovery of thyroid function and immune abnormality is not consistent, and the recovery of GD is more significant than that of GD / T2DM.