title: The dawn phenomenon in type 2 diabetes: how to assess it in clinical practice?
abstract: OBJECTIVE
  The study was aimed at determining whether the dawn phenomenon in type 2 diabetes (T2D) can be predicted and quantified using simple and easily accessible glucose determinations.
  
  
  METHODS
  A total of 210 non-insulin-treated persons with T2D underwent continuous glucose monitoring (CGM). The dawn phenomenon was quantified as the absolute increment from the nocturnal glucose nadir to the pre-breakfast value (Δdawn, mg/dL). Pre-lunch (preL) and pre-dinner (preD) glucose, and their averaged values (preLD), were compared with the nocturnal nadir. These pre-meal values were subtracted from the pre-breakfast values. The differences obtained (Δpre-mealL, Δpre-meal D and Δpre-meal LD) were correlated with Δdawn values. The receiver operating characteristic (ROC) curve was used to select the optimal Δpre-meal value that best predicted a dawn phenomenon, set at a threshold of 20mg/dL.
  
  
  RESULTS
  All pre-meal glucose levels and differences from pre-breakfast values (Δpre-meal) significantly correlated (P<0.0001) with the nocturnal nadir and Δdawn values, respectively. The strongest correlations were observed for the parameters averaged at preL and preD time points: r=0.83 for preLD and r=0.58 for Δpre-meal LD. ROC curve analysis indicated that the dawn phenomenon at a threshold of 20mg/dL can be significantly predicted by a Δpre-meal LD cut off value of 10mg/dL. The relationship between Δdawn (Y, mg/dL) and Δpre-meal LD (X, mg/dL) was Y=0.49 X+15.
  
  
  CONCLUSIONS
  The self-monitoring of preprandial glucose values at the three main mealtimes can predict the presence/absence of the dawn phenomenon, and permits reliable assessment of its magnitude without requiring continuous overnight glucose monitoring.
authors.affiliation: Institute of Clinical Research, University Montpellier 1, France. Electronic address: louis.monnier@inserm.fr.
authors.forename: L
authors.initials: L
authors.lastname: Monnier
authors.affiliation: Institute of Clinical Research, University Montpellier 1, France.
authors.forename: C
authors.initials: C
authors.lastname: Colette
authors.affiliation: Department of Endocrinology, Hospital Pitié-Salpétrière, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Dejager
authors.affiliation: Diabetes Research Group, Swansea University, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Owens
mesh_terms: D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D006801:Humans; D006943:Hyperglycemia / Q000097:blood*; D008297:Male; D062407:Meals; D008875:Middle Aged
chemical_list: D001786:Blood Glucose
keywords: Dawn phenomenon; Glucose monitoring; Type 2 diabetes