title: Bimodal distribution of glucose is not universally useful for diagnosing diabetes.
abstract: OBJECTIVE
  Bimodality in the distribution of glucose has been used to define the cut point for the diagnosis of diabetes. Previous studies on bimodality have primarily been in populations with a high prevalence of type 2 diabetes, including one study in a white Caucasian population. All studies included participants with known diabetes. The aim of this study was to assess whether a bimodal structure is a general phenomenon in fasting plasma glucose (FPG) and 2-h plasma glucose that is useful for deriving a common cut point for diabetes in populations of different origin, both including and excluding known diabetes.
  
  
  METHODS
  The Evaluation of Screening and Early Detection Strategies for Type 2 Diabetes and Impaired Glucose Tolerance (DETECT-2) project is an international collaboration pooling surveys from all continents. These studies include surveys in which plasma glucose was measured during an oral glucose tolerance test; in total, 43 studies (135,383 participants) from 27 countries were included. A mixture of two normal distributions was fitted to plasma glucose levels, and a cut point for normal glycemia was estimated as their intersection. In populations with a biologically meaningful cut point, bimodality was tested for significance.
  
  
  RESULTS
  Distributions of FPG and 2-h plasma glucose did not, in general, produce bimodal structures useful for deriving cut points for diabetes. When present, the cut points produced were inconsistent over geographical regions.
  
  
  CONCLUSIONS
  Deriving cut points for normal glycemia from distributions of FPG and 2-h plasma glucose does not appear to be suitable for defining diagnostic cut points for diabetes.
authors.affiliation: Steno Diabetes Center, Gentofte, Denmark. dtvs@steno.dk
authors.forename: Dorte
authors.initials: D
authors.lastname: Vistisen
authors.forename: Stephen
authors.initials: S
authors.lastname: Colagiuri
authors.forename: Knut
authors.initials: K
authors.lastname: Borch-Johnsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000032:analysis*; D002648:Child; D003625:Data Collection; D003920:Diabetes Mellitus / Q000175:diagnosis* / Q000453:epidemiology; D005215:Fasting / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D001786:Blood Glucose