Abstract: Objective To study the pancreatic islet β-cell function and insulin resistance of diabetic gastroparesis (DGP). Methods 31 subjects with normal glucose tolerance (NGT), 32 subjects with impaired glucose tolerance(IGT), 38 subjects with type 2 diabetes mellitus (T2DM) and 31 subjects with DGP were en-rolled in the study, assessed by steamed bread meal tests, the plasma glucose and insulin at 0, 30, 60, 120 and 180 min were respectively measured by using glucose oxidase and radioimmunoassay, investigate the changes of area under insulin cure (INSAUC), Homa-insulin resistance (Homa-IR) index and modified β-cell function index (MBCI). Results The INSAUC ofIGT, T2DM, NGT and DGP fell in turn, there were signif-icantly differences among the groups. The MBCI of NGT, IGT, T2DM and DGP fell in turn, there were significantly differences among the groups. The Homa-IR index of NGT, IGT, DGP and T2DM rose in turn, there were significantly differences among the groupsexcept between T2DM and DGP. Conclusions The pancreatic islet β-cell function of DGP was worse than NGT, IGT and T2DM, and the insulin resistance was stronger than NGT and IGT.