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Item
#5
Caffeine
Can Decrease Insulin Sensitivity
A
component of popular beverages decreases insulin sensitivity by
15%
Caffeine
is a central stimulant that increases the release of
catecholamines. As a component of popular beverages, caffeine
is widely used around the world. Its pharmacological effects
are predominantly due to adenosine receptor antagonism and
include release of catecholamines.
It was hypothesized that caffeine reduces
insulin sensitivity, either due to catecholamines and/or
as a result of blocking adenosine-mediated stimulation of
peripheral glucose uptake.
The
study design used hyperinsulinemic-euglycemic glucose
clamps used to assess insulin sensitivity. Caffeine or
placebo was administered intravenously to 12 healthy volunteers
in a randomized, double-blind, crossover design.
Measurements included plasma levels of insulin,
catecholamines, free fatty acids (FFAs), and
hemodynamic parameters. Insulin sensitivity was
calculated as whole-body glucose uptake corrected for the insulin
concentration. In a second study, the adenosine reuptake inhibitor
dipyridamole was tested using an identical protocol in
10 healthy subjects.
The
results showed caffeine decreased insulin sensitivity by
15% (P < 0.05 vs. placebo). After caffeine
administration, plasma FFAs increased (P <
0.05) and remained higher than during placebo. Plasma
epinephrine increased fivefold (P < 0.0005), and
smaller increases were recorded in plasma norepinephrine (P
< 0.02) and blood pressure (P < 0.001). Dipyridamole
did not alter insulin sensitivity and only increased plasma
norepinephrine (P < 0.01).
The
conclusions showed that caffeine can decrease insulin
sensitivity in healthy humans, possibly as a result of
elevated plasma epinephrine levels. Because
dipyridamole did not affect glucose uptake, peripheral
adenosine receptor antagonism does not appear to contribute
to this effect. Diabetes
Care 25:364-369, 2002
================================
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YOU KNOW?
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use of HMG CoA reductase inhibitors has contributed to
a marked reduction in mortality in cardiovascular deaths, the
benefit in type 2 diabetes has been disappointing.
By
referring your friends and colleagues to Diabetes in Control you
can win a free scholarship or expense check for the 2002 AADE
conference in Philadelphia.
http://www.diabetesincontrol.com/scholorship.shtml
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