Effects of chronic coffee consumption on glucose kinetics in the conscious rat

• Published in: Canadian journal of physiology and pharmacology Vol. 85; no. 8; pp. 823 - 830
• Main Authors: Shearer, J, Sellars, E.A, Farah, A, Graham, T.E, Wasserman, D.H
• Format: Journal Article
• Language: English
• Published: Ottawa, ON National Research Council of Canada 01.08.2007; NRC Research Press; Canadian Science Publishing NRC Research Press
• Subjects: action de l'insuline; Animal experimentation; animal model; Animals; Biological and medical sciences; Caffeine; Caffeine - pharmacology; café; Carotid arteries; Carotid artery; Catheters; Coffee; Diabetes; Diabetes mellitus (non-insulin dependent); diabète; Diet; Drinking water; Epidemiology; Evaluation; Experiments; Fundamental and applied biological sciences. Psychology; Glucose; Glucose - metabolism; High fat diet; Insulin; insulin action; Insulin resistance; Isotopes; Jugular vein; Male; Metabolism; modèle animal; Perfusion; Physiological aspects; Rats; Rats, Sprague-Dawley; Rodents; tracer; traceur; Veins & arteries; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Canada; Endocrinopathy; Animal model; Pancreatic hormone; Vertebrata; Chronic; Mammalia; Rat; Diabetes mellitus; Rodentia; Kinetics; Glucose; Insulin
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/Y07-070

Epidemiological studies indicate that regular coffee consumption reduces the risk of developing type 2 diabetes. Despite these findings, the biological mechanisms by which coffee consumption exerts these effects are unknown. The aim of this study was twofold: to develop a rat model that would further delineate the effects of regular coffee consumption on glucose kinetics, and to determine whether coffee, with or without caffeine, alters the actions of insulin on glucose kinetics in vivo. Male Sprague-Dawley rats were fed a high-fat diet for 4 weeks in combination with one of the following: (i) drinking water as placebo (PL), (ii) decaffeinated coffee (2 g/100 mL) (DC), or (iii) alkaloid caffeine (20 mg/100 mL) added to decaffeinated coffee (2 g/100 mL) (CAF). Catheters were chronically implanted in a carotid artery and jugular vein for sampling and infusions, respectively. Recovered animals (5 days postoperative) were fasted for 5 h before hyperinsulinemic-euglycemic clamps (2 mU·kg -1 ·min -1 ). Glucose was clamped at 6 mmol/L and isotopes (2-deoxy-[ 14 C]glucose and [3- 3 H]glucose) were administered to obtain indices of whole-body and tissue-specific glucose kinetics. Glucose infusion rates and measures of whole-body metabolic clearance were greater in DC than in PL or CAF, indicating increased whole-body insulin sensitivity. As the only difference between DC and CAF was the addition of alkaloid caffeine, it can be concluded that caffeine antagonizes the beneficial effects of DC. Given these findings, decaffeinated coffee may represent a nutritional means of combating insulin resistance.