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.

This will be a randomized, double-blind, placebo-controlled, parallel group study 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.which will be conducted in 8 diabetes centres and/or nephropathy departments in China. After a 4-week run- in period, 232 participants are randomized (1:1) to either premixed insulin combined with linagliptin (5mg/d) group (also named combined group) or premixed insulin alone group (also named insulin group) for 12 weeks. Finally, the primary endpoint is glucose variability indicated by MAGE, secondary endpoints include HbA1c, FPG, PPG, LAGE, SDBG, PT10.0, PT3.9, 1h fasting MBG, 3h postprandial MBG, insulin dosage, hypoglycemia and body weight.

Inclusion Criteria:

1. Type 2 diabetic patients who were treated with insulin regimen;
2. Ages eligible for study:18 years to 80 years;
3. The patients with end-stage kidney disease receiving a regular peritoneal dialysis for at least 3 months;
4. HbA1c ranging from 6.5%-10.5% when screening and randomizing ;
5. Body mass index ranging from 21 to 35 kg/m2.

Exclusion Criteria:

1. Having any severe acute or chronic diabetic complications
2. Blood aminotransferase level rising up more than 2 times of the upper normal limit
3. Any severe cardiac disease, severe systemic diseases or malignant tumour
4. Female patients incline to be pregnant
5. Being treated with corticosteroid, immunosuppressing drugs or cytotoxic drugs
6. Poor compliance