title: Caffeine ingestion is associated with reductions in glucose uptake independent of obesity and type 2 diabetes before and after exercise training.
abstract: OBJECTIVE
  We investigated the effect of caffeine ingestion on insulin sensitivity in sedentary lean men (n = 8) and obese men with (n = 7) and without (n = 8) type 2 diabetes. We also examined whether chronic exercise influences the relationship between caffeine and insulin sensitivity in these individuals.
  
  
  METHODS
  Subjects underwent two hyperinsulinemic-euglycemic clamp procedures, caffeine (5 mg/kg body wt) and placebo, in a double-blind, randomized manner before and after a 3-month aerobic exercise program. Body composition was measured by magnetic resonance imaging.
  
  
  RESULTS
  At baseline, caffeine ingestion was associated with a significant reduction (P < 0.05) in insulin sensitivity by a similar magnitude in the lean (33%), obese (33%), and type 2 diabetic (37%) groups in comparison with placebo. After exercise training, caffeine ingestion was still associated with a reduction (P < 0.05) in insulin sensitivity by a similar magnitude in the lean (23%), obese (26%), and type 2 diabetic (36%) groups in comparison with placebo. Exercise was not associated with a significant increase in insulin sensitivity in either the caffeine or placebo trials, independent of group (P > 0.10).
  
  
  CONCLUSIONS
  Caffeine consumption is associated with a substantial reduction in insulin-mediated glucose uptake independent of obesity, type 2 diabetes, and chronic exercise.
authors.affiliation: School of Physical and Health Education, Queen's University, Kingston, Ontario, Canada, K7L 3N6.
authors.forename: SoJung
authors.initials: S
authors.lastname: Lee
authors.forename: Robert
authors.initials: R
authors.lastname: Hudson
authors.forename: Katherine
authors.initials: K
authors.lastname: Kilpatrick
authors.forename: Terry E
authors.initials: TE
authors.lastname: Graham
authors.forename: Robert
authors.initials: R
authors.lastname: Ross
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000284:Administration, Oral; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D002149:Energy Intake; D015444:Exercise / Q000502:physiology*; D015309:Glucose Clamp Technique; D006801:Humans; D006946:Hyperinsulinism; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D009765:Obesity / Q000097:blood* / Q000503:physiopathology
chemical_list: D001786:Blood Glucose; D007328:Insulin; D002110:Caffeine