It is unclear whether acute hyperglycemia impairs exercise performance in T1D. To address this question we compared different exercise performance measures under 3 different conditions: euglycemia with basal insulin, hyperglycemia with basal insulin and hyperglycemia with low insulin.

In a randomized, counter-balanced, blinded study design, we studied 12 recreationally active individuals with T1D (8 males, 4 females, 17.9 ± 3.9 years, HbA1c 7.7 ± 1.0%, mean ± SD). Each completed exercise testing under 3 conditions: euglycemia (5 mM) with basal insulin (20 mU/m2 BSA/min) and hyperglycemia (17 mM) with basal insulin and hyperglycemia with low insulin (5 mU/m2 BSA/min). The clamp technique was used to achieve study conditions which were maintained for at least 60 min prior to exercise. Standardised exercise performance assessment consisted of 6 tests: a single cycle ergometer V˙2 peak test and the following tests performed in triplicate: 6-sec maximal sprint cycling, vertical jump, grip strength, single leg static balance, and modified Star Excursion Balance Test. Ten simple and choice reaction times were also performed.

Target glucose levels were achieved in all subjects: 4.9 ± 0.03 mM for euglycemia and 17.3 ± 0.04 mM for hyperglycemia (mean ± SE). Mean exercise testing duration was 110 min (range 90-130 min) with no observed ketosis. Analysis of the 6 exercise performance tests using mixed method models did not show any consistent difference in performance between the 3 study conditions. Choice reaction time was slower in hyperglycemia with low insulin compared to the other conditions (p<0.01).

This is the first study to comprehensively assess the effect of acute hyperglycemia on exercise performance. Our findings show that hyperglycemia in either basal or low insulin condition does not impair exercise performance as measured by a combination of maximal muscle power and strength, postural balance, and maximal aerobic capacity in recreationally active individuals with T1D.


K. Rothacker: None. S. Armstrong: None. G.J. Smith: None. N. Benjanuvatra: None. B.S. Lay: None. P.A. Fournier: None. P. Adolfsson: Advisory Panel; Self; Abbott, Eli Lilly and Company, Roche Diagnostics Corporation. Speaker's Bureau; Self; JDRF, Nordic Infucare, Rubin Medical. T. Jones: None. E.A. Davis: None.

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