 In china, there are the most population of type 2 diabetes mellitus DM among the world and DM becomes currently the second cause for end-stage renal disease ESRD. Nearly 50 of insulin-treated PD patients in clinical practice are treated with premixed insulin. Glycemic control in them is very difficult to be achieved mainly due to the uremic status of these patients and glucose exposure from peritoneal dialysate, a higher glycemic variability and higher risk of hypoglycemia. Linagliptin, unlike other DPP-4 inhibitors, has a primarily non-renal elimination route, and does not require dose adjustment for any level of impaired renal function. The aim of this study is to evaluate the effect of linagliptin on glucose variability and glycemic control in peritoneal dialysis patients with type 2 diabetes who are inadequately controlled with premixed insulin therapy. 