title: Comparisons of studies on diabetic complications hampered by differences in GHb measurements.
abstract: OBJECTIVE
  To compare glycated hemoglobin (GHb) values of the relationship between glycemic control and complications of diabetes from laboratories involved in long-term studies (Steno, Oslo, Stockholm, Diabetes Control and Complications Trial, and Linköping.)
  
  
  METHODS
  Blood samples were collected from 25 subjects selected to represent the clinically relevant measurement range. Fresh whole-blood samples were distributed and analyzed within 4 days of sample collection. Pretreatment of samples and analyses of GHb were performed according to the routine method of each study's central or reference laboratory. Results from each laboratory were compared with the group mean, i.e., the mean of all results for each sample.
  
  
  RESULTS
  Regression analyses with the group mean values as independent variables and results from each laboratory as dependent variables showed that Oslo's result had a slope significantly different from the group mean. Laboratories used by the DCCT, Oslo, and Steno studies gave, on average, 0.4, 0.4, and 0.7% higher HbA1c readings than the group mean, respectively, while HbA1c results from Linköping and Stockholm were, on average, 0.6 and 1.0% lower, respectively.
  
  
  CONCLUSIONS
  There were large differences in GHb values among laboratories participating in studies of diabetic complications. The present data offer a guide to the comparison of results from the studies and underscores the need for standardization of GHb measurements.
authors.affiliation: Department of Internal Medicine, Faculty of Health Sciences, Linköping, Sweden.
authors.forename: C E
authors.initials: CE
authors.lastname: Kullberg
authors.forename: A
authors.initials: A
authors.lastname: Bergström
authors.forename: B
authors.initials: B
authors.lastname: Dinesen
authors.forename: L
authors.initials: L
authors.lastname: Larsson
authors.forename: R R
authors.initials: RR
authors.lastname: Little
authors.forename: D E
authors.initials: DE
authors.lastname: Goldstein
authors.forename: H J
authors.initials: HJ
authors.lastname: Arnqvist
mesh_terms: D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000097:blood; D005069:Evaluation Studies as Topic; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D009664:Norway; D012044:Regression Analysis; D015203:Reproducibility of Results; D013548:Sweden
chemical_list: D006442:Glycated Hemoglobin