Decaffeinated coffee and glucose metabolism in young men

Diabetes Care. 2010 Feb;33(2):278-80. doi: 10.2337/dc09-1539. Epub 2009 Nov 16.


Objective: The epidemiological association between coffee drinking and decreased risk of type 2 diabetes is strong. However, caffeinated coffee acutely impairs glucose metabolism. We assessed acute effects of decaffeinated coffee on glucose and insulin levels.

Research design and methods: This was a randomized, cross-over, placebo-controlled trial of the effects of decaffeinated coffee, caffeinated coffee, and caffeine on glucose, insulin, and glucose-dependent insulinotropic polypeptide (GIP) levels during a 2-h oral glucose tolerance test (OGTT) in 11 young men.

Results: Within the first hour of the OGTT, glucose and insulin were higher for decaffeinated coffee than for placebo (P < 0.05). During the whole OGTT, decaffeinated coffee yielded higher insulin than placebo and lower glucose and a higher insulin sensitivity index than caffeine. Changes in GIP could not explain any beverage effects on glucose and insulin.

Conclusions: Some types of decaffeinated coffee may acutely impair glucose metabolism but less than caffeine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / drug effects
  • Blood Glucose / metabolism*
  • Caffeine / analysis
  • Caffeine / pharmacology*
  • Coffee*
  • Glucose Tolerance Test
  • Glutaminase / blood
  • Glutaminase / drug effects
  • Humans
  • Insulin / blood
  • Intracellular Signaling Peptides and Proteins / blood
  • Intracellular Signaling Peptides and Proteins / drug effects
  • Male
  • Placebos


  • Blood Glucose
  • Coffee
  • Insulin
  • Intracellular Signaling Peptides and Proteins
  • Placebos
  • TAX1BP3 protein, human
  • Caffeine
  • Glutaminase