title: CD26/DPP4 levels in peripheral blood and T cells in patients with type 2 diabetes mellitus.
abstract: BACKGROUND
  Dipeptidyl peptidase 4 (CD26/DPP4) is expressed on blood T cells and also circulates in a soluble form (sCD26/DPP4).
  
  
  OBJECTIVE
  We aimed to evaluate blood T cell and circulating CD26/DPP4 and its association with metabolic parameters in patients with type 2 diabetes mellitus (T2DM).
  
  
  METHODS
  We measured CD26/DPP4 expression (percentage of CD26(+) cells using flow cytometry) on CD4(+) and CD8(+) T cells, serum CD26/DPP4 level and activity, and various metabolic parameters in T2DM patients not on DPP4 inhibitor therapy (n = 148). Nondiabetic subjects (n = 50) were included as a control group.
  
  
  RESULTS
  Compared with the healthy controls, CD26/DPP4 expression on CD4(+) T cells and CD8(+) T cells was higher in T2DM patients. Serum CD26/DPP4 levels and enzymatic activities were also higher in patients with T2DM than in the control group only when metformin and/or thiazolidinedione-treated T2DM patients were excluded; metformin and/or thiazolidinedione-treated T2DM patients had lower values compared with other T2DM patients. Various parameters in T2DM patients were related to CD26/DPP4 expression on the T cells (hemoglobin A1c), serum sCD26/DPP4 (hemoglobin A1c and insulin resistance assessed by updated homeostasis model assessment), and serum CD26/DPP4 activity (insulin resistance assessed by updated homeostasis model assessment, γ-glutamyl transferase, and alanine aminotransferase) by multivariate analyses. After active glucose control for 12 weeks in drug-naive T2DM patients (n = 50), CD26/DPP4 expression on blood T cells was significantly decreased.
  
  
  CONCLUSIONS
  Our results suggest that the CD26/DPP4 level on blood T cells was associated with glucose control status in patients with T2DM.
authors.affiliation: Department of Internal Medicine, Jeju National University School of Medicine, Jeju, Republic of Korea 690-756.
authors.forename: Sang Ah
authors.initials: SA
authors.lastname: Lee
authors.forename: Young Ree
authors.initials: YR
authors.lastname: Kim
authors.forename: Eun Jin
authors.initials: EJ
authors.lastname: Yang
authors.forename: Eun-Jeong
authors.initials: EJ
authors.lastname: Kwon
authors.forename: Sun Hyung
authors.initials: SH
authors.lastname: Kim
authors.forename: Sung Ha
authors.initials: SH
authors.lastname: Kang
authors.forename: Doek Bae
authors.initials: DB
authors.lastname: Park
authors.forename: Byung-Chul
authors.initials: BC
authors.lastname: Oh
authors.forename: Jinseok
authors.initials: J
authors.lastname: Kim
authors.forename: Sang Taek
authors.initials: ST
authors.lastname: Heo
authors.forename: Gwanpyo
authors.initials: G
authors.lastname: Koh
authors.forename: Dae Ho
authors.initials: DH
authors.lastname: Lee
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000201:enzymology*; D018819:Dipeptidyl Peptidase 4 / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008687:Metformin / Q000627:therapeutic use; D008875:Middle Aged; D013601:T-Lymphocytes / Q000201:enzymology*; D045162:Thiazolidinediones / Q000627:therapeutic use
chemical_list: D001786:Blood Glucose; D045162:Thiazolidinediones; D008687:Metformin; C089946:2,4-thiazolidinedione; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4