title: Vitamin D deficiency is associated with depletion of circulating endothelial progenitor cells and endothelial dysfunction in patients with type 2 diabetes.
abstract: BACKGROUND
  Vitamin D (Vit-D) deficiency is associated with type 2 diabetes mellitus (DM) and endothelial dysfunction. The relationship of Vit-D deficiency with circulating endothelial progenitor cells and endothelial dysfunction in type 2 DM patients nonetheless remains unclear.
  
  
  OBJECTIVE
  We aimed to investigate the cross-sectional association of Vit-D status with brachial flow-mediated dilation (FMD) and circulating endothelial progenitor cell (EPC) numbers in type 2 DM patients.
  
  
  METHODS
  We conducted a cross-sectional study of 280 patients (59% male, aged 68 ± 10 yr) with type 2 DM recruited in outpatient clinics during the winter period.
  
  
  METHODS
  We measured serum 25-hydroxyvitamin D [25(OH)D] by an ELISA kit, circulating CD34+/kinase insert domain-containing receptor (KDR)+ and CD133+/KDR+ EPCs by flow cytometry and brachial artery FMD by vascular ultrasound, respectively.
  
  
  RESULTS
  The mean serum 25(OH)D concentration was 25.00 ± 9.17 ng/ml, and 34.3% of patients had Vit-D deficiency [25(OH)D < 20 ng/ml]. Serum 25(OH)D concentration had a significant correlation with hemoglobin A1c level [B = -0.018, 95% confidence interval (CI) -0.035 to -0.002, P = 0.032]. Patients with Vit-D deficiency status had significantly lower brachial FMD (mean difference -1.43%, 95% CI -2.31 to -0.55, P = 0.001) and CD133+/KDR+EPC counts (mean difference -0.12%, 95% CI -0.21 to -0.019, P = 0.022) than those with sufficient Vit-D status after adjustment for age, sex, and cardiovascular risk factors, including hemoglobin A1c levels.
  
  
  CONCLUSIONS
  Our results demonstrate that serum 25(OH)D status was significantly associated with brachial artery FMD and circulating CD133+/KDR+EPCs. This suggests that Vit-D deficiency might contribute to depletion of EPCs and endothelial dysfunction in patients with type 2 DM.
authors.affiliation: Cardiology Division, Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Yuen-Fung
authors.initials: YF
authors.lastname: Yiu
authors.forename: Yap-Hang
authors.initials: YH
authors.lastname: Chan
authors.forename: Kai-Hang
authors.initials: KH
authors.lastname: Yiu
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
authors.forename: Sheung-Wai
authors.initials: SW
authors.lastname: Li
authors.forename: Lai-Yung
authors.initials: LY
authors.lastname: Wong
authors.forename: Stephen W L
authors.initials: SW
authors.lastname: Lee
authors.forename: Sidney
authors.initials: S
authors.lastname: Tam
authors.forename: Eric W K
authors.initials: EW
authors.lastname: Wong
authors.forename: Bernard M Y
authors.initials: BM
authors.lastname: Cheung
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
mesh_terms: D000071916:AC133 Antigen; D000368:Aged; D000375:Aging / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000473:pathology* / Q000503:physiopathology*; D004100:Dihydroxycholecalciferols / Q000097:blood; D042783:Endothelial Cells / Q000473:pathology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D010455:Peptides / Q000378:metabolism; D012044:Regression Analysis; D012727:Sex Characteristics; D012907:Smoking / Q000097:blood; D013234:Stem Cells / Q000473:pathology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics; D014808:Vitamin D Deficiency / Q000473:pathology*; D049629:Waist-Hip Ratio
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D004100:Dihydroxycholecalciferols; D006442:Glycated Hemoglobin; D006023:Glycoproteins; D008055:Lipids; D010455:Peptides; D040301:Vascular Endothelial Growth Factor Receptor-2; C000606023:PROM1 protein, human