title: Reduced plasma total homocysteine concentrations in Type 1 diabetes mellitus is determined by increased renal clearance.
abstract: BACKGROUND
  Elevated plasma levels of total homocysteine are related to the development of vascular complications. Patients with diabetes mellitus are particularly at risk for the development of these complications. Several factors determine plasma total homocysteine including renal function.
  
  
  OBJECTIVE
  As early Type 1 diabetes is characterized by a relative glomerular hyperfiltration, increased renal clearance could contribute to decreased levels of homocysteine as observed in Type 1 diabetes mellitus. Therefore we investigated the relationship between plasma total homocysteine and the glomerular filtration rate (GFR).
  
  
  METHODS
  In 92 Type 1 diabetes patients and 44 control subjects, we measured GFR and effective renal plasma flow (ERPF) by means of continuous infusion of inulin and p-aminohippurate. Fasting plasma total homocysteine was measured using high performance liquid chromatography.
  
  
  RESULTS
  GFR (121 +/- 21 resp. 104 +/- 14 ml/min; P < 0.001) and ERPF (563 +/- 127 resp. 516 +/- 121 ml/min; P = 0.05) were significantly higher in Type 1 diabetes patients as compared with control subjects. Plasma total homocysteine was reduced in Type 1 diabetes patients as compared with control subjects (11.0 +/- 4.5 resp. 13.4 +/- 7 micromol/l; P = 0.01). Plasma total homocysteine was strongly correlated with GFR (Type 1 diabetes patients: r = -0.43, P < 0.001; control subjects: r = -0.39, P = 0.01).
  
  
  CONCLUSIONS
  GFR is a major determinant of plasma total homocysteine levels in Type 1 diabetes patients as well as control subjects. The reduced plasma total homocysteine levels in diabetes patients can be explained by an increased GFR.
authors.affiliation: Department of Internal Medicine, University Medical Center, Nijmegen, Nijmegen, The Netherlands.
authors.forename: B A J
authors.initials: BA
authors.lastname: Veldman
authors.forename: G
authors.initials: G
authors.lastname: Vervoort
authors.forename: H
authors.initials: H
authors.lastname: Blom
authors.forename: P
authors.initials: P
authors.lastname: Smits
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002851:Chromatography, High Pressure Liquid; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology*; D005260:Female; D005919:Glomerular Filtration Rate; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007328:Insulin; D007668:Kidney / Q000098:blood supply / Q000378:metabolism*; D008297:Male; D012039:Regional Blood Flow; D012044:Regression Analysis; D010130:p-Aminohippuric Acid
chemical_list: D007328:Insulin; D006710:Homocysteine; D010130:p-Aminohippuric Acid