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Caffeine's impairment of insulin‐mediated glucose disposal cannot be solely attributed to adrenaline in humans
Author(s) -
Battram D. S.,
Graham T. E.,
Dela F.
Publication year - 2007
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2007.130526
Subject(s) - caffeine , saline , medicine , placebo , endocrinology , pharmacology , pathology , alternative medicine
Caffeine (CAF) impedes insulin‐mediated glucose disposal (IMGD) and increases plasma adrenaline concentrations ([ADR]; 0.6 n m ). While the antagonism of ADR abolishes the CAF effect, infusion of ADR (0.75 n m ) has no effect on IMGD. We have now examined CAF and ADR in concert to determine whether or not they elicit an additive response on IMGD. We hypothesized that CAF + ADR would elicit a greater effect than either CAF or ADR alone (i.e. that CAF effects would not be solely attributed to ADR). Subjects ( n = 8) completed four trials in a randomized manner. An isoglycaemic–hyperinsulinaemic clamp was performed 30 min after the following treatments were administered: (1) placebo capsules and saline infusion ([ADR]= 0.29 n m ) (PL trial), (2) CAF capsules (dose = 5 mg kg −1 ) and saline infusion ([ADR]= 0.62 n m ) (CAF trial), (3) PL capsules and ADR infusion ([ADR]= 1.19 n m ) (ADR trial), and (4) CAF capsules (dose = 5 mg kg −1 ) and ADR infusion ([ADR]= 0.93 n m ) (CAF + ADR trial). As expected, CAF, ADR and CAF + ADR decreased ( P ≤ 0.05) IMGD compared to PL. CAF + ADR resulted in a more pronounced decrease in IMGD versus PL (42%) compared to CAF (26%) or ADR (24%) alone; however, the effect was not fully additive ( P = 0.08). Furthermore, CAF decreased IMGD to a similar magnitude as ADR despite a 50% lower [ADR]. In summary, while ADR contributes to the CAF‐induced impairment in IMGD, it is not solely responsible for caffeine's effects.