Impact of pre-exercise rapid-acting insulin reductions on ketogenesis following running in Type-1 diabetes

Bracken, R. M., West, D. J., Stephens, J. W., Kilduff, L. P., Luzio, Stephen Denis and Bain, S. C. 2011. Impact of pre-exercise rapid-acting insulin reductions on ketogenesis following running in Type-1 diabetes. Diabetic Medicine 28 (2) , pp. 218-222. 10.1111/j.1464-5491.2010.03162.x

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Abstract

Aim This study examined the effects of reductions to pre-exercise rapid-acting insulin dose on changes in blood beta-hydroxybutyrate, glucose, acid-base balance and counter-regulatory hormone responses to prolonged running in individuals with Type 1 diabetes. Methods Following ethical approval, seven participants with Type 1 diabetes (34 ± 2 years, BMI 27 ± 1 kg/m2) completed this study. After preliminary testing, participants attended the laboratory four times, each time consuming a 1.12MJ meal (60 g carbohydrate, 2 g fat, 2 g protein), with randomized amounts of their rapid-acting insulin: Full dose (mean 7.3 ± 0.2 units), 75% dose (mean 5.4 ± 0.1 units), 50% dose (mean 3.7 ± 0.1 units) or 25% dose (mean 1.8 ± 0.1 units). After 2-h rest, participants completed 45 min running at 70 ± 1% peak rate of oxygen consumption (VO2peak). Blood metabolites and hormones were recorded over the 2-h rest and 3-h recovery. Data were analysed using repeated-measures ANOVA. Results Serum insulin peaked at 60 min in all conditions and was lowest after 25% insulin dose compared with full dose (P = 0.03). After the 25% insulin dose immediately pre-exercise glucose concentration was higher than after the full or 50% dose (P < 0.05). Resting beta-hydroxybutyrate gradually decreased during 2-h rest (P < 0.05) with a similar post-exercise peak of beta-hydroxybutyrate at 3 h (P > 0.05). Post-exercise blood pH increased for 5 min to a similar extent with all insulin doses , but the rise with the 25% dose was less compared with the full dose (P = 0.01). Blood lactate and plasma catecholamines increased after running similarly with all insulin reduction conditions (P < 0.05). Blood glucose area under the curve (BGauc) after the 25% insulin dose was greater than after the 75% dose (P = 0.02). Conclusion Ketogenesis following running was not influenced by reductions in pre-exercise rapid-acting insulin dose. This important preparatory strategy aids preservation of blood glucose but poses no greater risk to exercise-induced ketone body formation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Subjects:	R Medicine > R Medicine (General)
Uncontrolled Keywords:	acid-base balance, carbohydrate supplementation, exercise, ketoacidosis
Publisher:	Wiley
ISSN:	0742-3071
Last Modified:	04 Jun 2017 03:48
URI:	https://orca.cardiff.ac.uk/id/eprint/26982

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