Caffeinated coffee consumption impairs blood glucose homeostasis in response to high and low glycemic index meals in healthy men

Am J Clin Nutr. 2008 May;87(5):1254-61. doi: 10.1093/ajcn/87.5.1254.


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.

Design: 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.

Conclusion: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Area Under Curve
  • Blood Glucose / drug effects
  • Blood Glucose / metabolism*
  • C-Peptide / blood
  • Caffeine / pharmacology*
  • Coffee / chemistry*
  • Cross-Over Studies
  • Dietary Carbohydrates / pharmacokinetics*
  • Edible Grain
  • Glucose Tolerance Test
  • Glycemic Index*
  • Humans
  • Insulin / blood
  • Male
  • Middle Aged


  • Blood Glucose
  • C-Peptide
  • Coffee
  • Dietary Carbohydrates
  • Insulin
  • Caffeine