Caffeine Ingestion Is Associated With Reductions in Glucose Uptake Independent of Obesity and Type 2 Diabetes Before and After Exercise Training
- SoJung Lee, PHD1,
- Robert Hudson, MD, PHD2,
- Katherine Kilpatrick, MD3,
- Terry E. Graham, PHD4 and
- Robert Ross, PHD12
- 1School of Physical and Health Education, Queen’s University, Kingston, Ontario, Canada
- 2Department of Medicine, Division of Endocrinology and Metabolism, Queen’s University, Kingston, Ontario, Canada
- 3Department of Medicine, Division of Geriatrics, Queen’s University, Kingston, Ontario, Canada
- 4Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- Address correspondence and reprint requests to Robert Ross, PhD, School of Physical and Health Education, Queen’s University, Kingston, Ontario, Canada, K7L 3N6. E-mail: rossr{at}post.queensu.ca
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.
RESEARCH DESIGN AND 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.
Footnotes
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A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
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- Accepted December 6, 2004.
- Received October 8, 2004.
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