title: Continuous glucose monitoring to assess the ecologic validity of dietary glycemic index and glycemic load.
abstract: BACKGROUND
  The circumstances under which the glycemic index (GI) and glycemic load (GL) are derived do not reflect real-world eating behavior. Thus, the ecologic validity of these constructs is incompletely known.
  
  
  OBJECTIVE
  This study examined the relation of dietary intake to glycemic response when foods are consumed under free-living conditions.
  
  
  METHODS
  Participants were 26 overweight or obese adults with type 2 diabetes who participated in a randomized trial of lifestyle modification. The current study includes baseline data, before initiation of the intervention. Participants wore a continuous glucose monitor and simultaneously kept a food diary for 3 d. The dietary variables included GI, GL, and intakes of energy, fat, protein, carbohydrate, sugars, and fiber. The glycemic response variables included AUC, mean and SD of continuous glucose monitoring (CGM) values, percentage of CGM values in euglycemic and hyperglycemic ranges, and mean amplitude of glycemic excursions. Relations between daily dietary intake and glycemic outcomes were examined.
  
  
  RESULTS
  Data were available from 41 d of monitoring. Partial correlations, controlled for energy intake, indicated that GI or GL was significantly associated with each glycemic response outcome. In multivariate analyses, dietary GI accounted for 10% to 18% of the variance in each glycemic variable, independent of energy and carbohydrate intakes (P < 0.01).
  
  
  CONCLUSIONS
  The data support the ecologic validity of the GI and GL constructs in free-living obese adults with type 2 diabetes. GI was the strongest and most consistent independent predictor of glycemic stability and variability.
authors.affiliation: Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, 19104-3309, USA. fabricat@mail.med.upenn.edu
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Fabricatore
authors.forename: Cara B
authors.initials: CB
authors.lastname: Ebbeling
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Wadden
authors.forename: David S
authors.initials: DS
authors.lastname: Ludwig
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring / Q000379:methods; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications; D004032:Diet; D015930:Diet Records; D004040:Dietary Carbohydrates / Q000378:metabolism*; D002149:Energy Intake; D005260:Female; D038321:Glycemic Index; D006801:Humans; D006943:Hyperglycemia / Q000097:blood; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000097:blood* / Q000150:complications; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates
references.citation: Diabetes Care. 2011 Jan;34 Suppl 1:S11-61
references.pmid: 21193625
references.citation: Diabetes. 1970 Sep;19(9):644-55
references.pmid: 5469118
references.citation: Am J Clin Nutr. 1986 Jan;43(1):167-72
references.pmid: 3942088
references.citation: JAMA. 2006 Apr 12;295(14):1681-7
references.pmid: 16609090
references.citation: Diabetes Res Clin Pract. 2011 Apr;92(1):37-45
references.pmid: 21208675
references.citation: Diabetes Technol Ther. 2006 Jun;8(3):318-25
references.pmid: 16800753
references.citation: Diabetes Care. 2006 Dec;29(12):2644-9
references.pmid: 17130198
references.citation: Diabetes Care. 2003 Feb;26(2):548-9
references.pmid: 12547905
references.citation: Diabetes Care. 2003 Apr;26(4):1153-7
references.pmid: 12663589
references.citation: Diabetes Care. 1997 Apr;20(4):545-50
references.pmid: 9096978
references.citation: J Clin Endocrinol Metab. 2006 Jun;91(6):2062-7
references.pmid: 16537685
references.citation: Diabetes Care. 2009 Sep;32(9):1600-2
references.pmid: 19542012
references.citation: Am J Clin Nutr. 2002 Jul;76(1):290S-8S
references.pmid: 12081854
references.citation: Am J Clin Nutr. 1981 Mar;34(3):362-6
references.pmid: 6259925
references.citation: Am J Clin Nutr. 2011 May;93(5):984-96
references.pmid: 21325437
references.citation: J Nutr. 2003 Sep;133(9):2728-32
references.pmid: 12949357
references.citation: J Pharmacokinet Biopharm. 1992 Jun;20(3):211-26
references.pmid: 1522479
references.citation: Diabetes Technol Ther. 2008 Oct;10(5):385-90
references.pmid: 18715215
references.citation: Diabetes Care. 1987 Nov-Dec;10(6):759-63
references.pmid: 3322731