title: Caffeinated coffee consumption impairs blood glucose homeostasis in response to high and low glycemic index meals in healthy men.
abstract: BACKGROUND
  The ingestion of caffeine (5 mg/kg body weight) and a 75-g oral glucose load has been shown to elicit an acute insulin-insensitive environment in healthy and obese individuals and in those with type 2 diabetes.
  
  
  OBJECTIVE
  In this study we investigated whether a similar impairment in blood glucose management exists when coffee and foods typical of a Western diet were used in a similar protocol.
  
  
  METHODS
  Ten healthy men underwent 4 trials in a randomized order. They ingested caffeinated (5 mg/kg) coffee (CC) or the same volume of decaffeinated coffee (DC) followed 1 h later by either a high or low glycemic index (GI) cereal (providing 75 g of carbohydrate) mixed meal tolerance test.
  
  
  RESULTS
  CC with the high GI meal resulted in 147%, 29%, and 40% greater areas under the curve for glucose (P < 0.001), insulin (NS), and C-peptide (P < 0.001), respectively, compared with the values for DC. Similarly, with the low GI treatment, CC elicited 216%, 44%, and 36% greater areas under the curve for glucose (P < 0.001), insulin (P < 0.01), and C-peptide (P < 0.01), respectively. Insulin sensitivity was significantly reduced (40%) with the high GI treatment after CC was ingested compared with DC; with the low GI treatment, CC ingestion resulted in a 29% decrease in insulin sensitivity, although this difference was not significant.
  
  
  CONCLUSIONS
  The ingestion of CC with either a high or low GI meal significantly impairs acute blood glucose management and insulin sensitivity compared with ingestion of DC. Future investigations are warranted to determine whether CC is a risk factor for insulin resistance.
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Lesley L
authors.initials: LL
authors.lastname: Moisey
authors.forename: Sita
authors.initials: S
authors.lastname: Kacker
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Bickerton
authors.forename: Lindsay E
authors.initials: LE
authors.lastname: Robinson
authors.forename: Terry E
authors.initials: TE
authors.lastname: Graham
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood; D002110:Caffeine / Q000494:pharmacology*; D003069:Coffee / Q000737:chemistry*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000493:pharmacokinetics*; D002523:Edible Grain; D005951:Glucose Tolerance Test; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D003069:Coffee; D004040:Dietary Carbohydrates; D007328:Insulin; D002110:Caffeine