title: Plasma 1,5-anhydroglucitol concentrations are influenced by variations in the renal threshold for glucose.
abstract: OBJECTIVE
  Measurement of serum 1,5-anhydroglucitol (1,5AG) concentrations has been proposed as an alternative to HbA1c as both a marker of diabetic glycaemic control and as a screening test for diabetes. The sugar competes with glucose for renal tubular reabsorption, so hyperglycaemia leads to reduced serum 1,5AG concentrations through increased urinary loss. This study has sought to establish whether plasma 1,5AG can be influenced by not only hyperglycaemia, but by variations in renal threshold for glucose.
  
  
  METHODS
  Thirty-eight pregnant women (median age 30 years, range 20-43) found to be normoglycaemic after a 75-g carbohydrate load had plasma 1,5AG and urine glucose measured.
  
  
  RESULTS
  Using multivariate analysis, the presence and degree of detectable glycosuria at 2 h post glucose load was strongly predictive of a low plasma 1,5AG concentration (P=0.0012) independently of fasting plasma glucose (P=0.96), 2 h glucose (P=0.029), subject age (P=0.97) and gestation (P=0.36). Thus, when matched for plasma glucose areas under the glucose load curve, 16 glycosuric subjects had significantly lower 1,5AG concentrations compared to 16 nonglycosuric ones (median 1,5AG 46 micromol/l (IQR 30-56) vs. 72 micromol/l (IQR 55-79, P=0.017).
  
  
  CONCLUSIONS
  People with the same glucose tolerance may demonstrate variable plasma 1,5AG concentrations depending on their renal threshold for glucose. This inherent characteristic is likely to limit the usefulness of the test when monitoring or screening for diabetes.
authors.affiliation: Department of Clinical Biochemistry, Hull Royal Infirmary, UK. eric_kilpatrick@hotmail.com
authors.forename: E S
authors.initials: ES
authors.lastname: Kilpatrick
authors.forename: B G
authors.initials: BG
authors.lastname: Keevilt
authors.forename: K L
authors.initials: KL
authors.lastname: Richmond
authors.forename: P
authors.initials: P
authors.lastname: Newland
authors.forename: G M
authors.initials: GM
authors.lastname: Addison
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003847:Deoxyglucose / Q000097:blood*; D005260:Female; D005865:Gestational Age; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D006029:Glycosuria; D006801:Humans; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000097:blood / Q000175:diagnosis* / Q000652:urine
chemical_list: D001786:Blood Glucose; C006584:1,5-anhydroglucitol; D003847:Deoxyglucose; D005947:Glucose