title: Impaired microvascular endothelial function in vitamin D-deficient diabetic nephropathy patients.
abstract: OBJECTIVE
  This study aims to compare microvascular endothelial function between vitamin D-deficient and nondeficient groups of patients with diabetic nephropathy. Serum levels of the inflammatory marker high-sensitivity C-reactive protein (hsCRP) were also measured.
  
  
  METHODS
  This prospective cross-sectional study involved 70 patients with diabetic nephropathy; 40 were categorized into the group with nondeficient serum 25-hydroxyvitamin D levels [25(OH)D >50 nmol/l], whereas 30 patients were categorized to the group with deficient serum 25(OH)D (<50 nmol/l). Microvascular endothelial function was determined using laser Doppler fluximetry and the process of iontophoresis. Acetylcholine and sodium nitroprusside were used to determine endothelium-dependent and independent vasodilatation.
  
  
  RESULTS
  Mean age of patients was 56.7 ± 3.8 years; 50 were men, whereas 20 were women. Mean serum 25(OH)D in the vitamin D-nondeficient group was 69.4 ± 2.9 nmol/l; the level in the vitamin D-deficient group was 42.1 ± 1.3 nmol/l, P < 0.001. Endothelium-dependent vasodilatation was lower in the vitamin D-deficient group compared with the vitamin D-nondeficient group (23.6 ± 2.7 versus 37.3 ± 3.8 arbitrary units, P = 0.004). No significant differences were observed between the two groups in their hsCRP levels, mean age, estimated glomerular filtration rate, systolic blood pressure (SBP) and diastolic blood pressure (DBP) and glycosylated haemoglobin.
  
  
  CONCLUSIONS
  Microvascular endothelial function was significantly reduced in diabetic nephropathy patients with deficient vitamin D levels compared with those with nondeficient levels.
authors.affiliation: Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia.
authors.forename: S
authors.initials: S
authors.lastname: Munisamy
authors.forename: M D
authors.initials: MD
authors.lastname: Kamaliah
authors.forename: A H
authors.initials: AH
authors.lastname: Suhaidarwani
authors.forename: W M
authors.initials: WM
authors.lastname: Zahiruddin
authors.forename: A H
authors.initials: AH
authors.lastname: Rasool
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D003925:Diabetic Angiopathies / Q000097:blood / Q000503:physiopathology*; D003928:Diabetic Nephropathies / Q000097:blood / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D007478:Iontophoresis; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation; D055806:Microvessels / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D008875:Middle Aged; D011446:Prospective Studies; D012867:Skin / Q000098:blood supply*; D014664:Vasodilation; D014665:Vasodilator Agents / Q000008:administration & dosage; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000503:physiopathology*
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators; D014665:Vasodilator Agents; D014807:Vitamin D; D002097:C-Reactive Protein; C104450:25-hydroxyvitamin D