title: Continuous glucose monitoring and its relationship to hemoglobin A1c and oral glucose tolerance testing in obese and prediabetic youth.
abstract: BACKGROUND
  The optimal screening test for diabetes and prediabetes in obese youth is controversial.
  
  
  OBJECTIVE
  We examined whether glycosylated hemoglobin (HbA1c) or the oral glucose tolerance test (OGTT) is a better predictor of free-living glycemia as measured by continuous glucose monitoring (CGM).
  
  
  METHODS
  This was a cross-sectional study of youth 10-18 years old, body mass index (BMI) 85th percentile or greater, with diabetes risk factors.
  
  
  METHODS
  Participants (n = 118) with BMI 85th percentile or greater, not on medications for glucose management, were recruited from primary care and pediatric endocrinology clinics around Denver, Colorado.
  
  
  METHODS
  HbA1c, fasting plasma glucose, and 2-hour glucose were collected and all participants wore a blinded CGM for 72 hours.
  
  
  METHODS
  CGM outcomes were determined and descriptive statistics calculated. Performance characteristics at current American Diabetes Association cutpoints were compared with CGM outcomes.
  
  
  RESULTS
  CGM data were successfully collected on 98 obese youth. Those with prediabetes had significantly higher average glucose, area under the curve (AUC), peak glucose, and time greater than 120 and greater than 140 mg/dL (P < .01) on CGM than youth with normal HbA1c or OGTT. HbA1c had a greater magnitude of correlation to CGM average glucose, AUC, and minimum glucose; 2-hour glucose had a greater magnitude of correlation to CGM SD, peak glucose, and time greater than 140 and greater than 200 mg/dL. However, there were no overall differences in the strength comparisons between 2-hour glucose and HbA1c correlations to CGM outcomes.
  
  
  CONCLUSIONS
  In obese youth, HbA1c and 2-hour glucose performed equally well at predicting free-living glycemia on CGM, suggesting that both are valid tests for dysglycemia screening.
authors.affiliation: Department of Pediatrics, Division of Pediatric Endocrinology (C.L.C., L.N., K.J.N., P.S.Z., M.M.K.), and Department of Pediatrics, Administrative Division (L.P.), University of Colorado Denver, Aurora, Colorado 80045.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Chan
authors.forename: Laura
authors.initials: L
authors.lastname: Pyle
authors.forename: Lindsey
authors.initials: L
authors.lastname: Newnes
authors.forename: Kristen J
authors.initials: KJ
authors.lastname: Nadeau
authors.forename: Philip S
authors.initials: PS
authors.lastname: Zeitler
authors.forename: Megan M
authors.initials: MM
authors.lastname: Kelsey
mesh_terms: D000293:Adolescent; D001786:Blood Glucose / Q000032:analysis; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation / Q000379:methods; D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D005215:Fasting / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D009765:Obesity / Q000097:blood*; D011236:Prediabetic State / Q000097:blood*
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human