Elsevier

Metabolism

Volume 53, Issue 9, September 2004, Pages 1126-1130
Metabolism

Carbohydrate requirement and insulin concentration during moderate exercise in type 1 diabetic patients

https://doi.org/10.1016/j.metabol.2004.03.015Get rights and content

Abstract

The lack in control of insulin release combined with an inadequate carbohydrate (CHO) ingestion accounts for the occurrence of frequent metabolic unbalances during exercise in type 1 diabetic patients. The aim of the study was to quantify, in these patients, the CHO requirement to prevent hypoglycemia during moderate exercise performed at different time intervals after morning subcutaneous insulin injection. Twelve type 1 diabetic patients and 12 well-matched healthy subjects cycled 4 times for 1 hour at a constant workload. The rate of glucose oxidation was calculated continuously by indirect calorimetry throughout the exercise, while blood parameters were assessed periodically and orally given CHO were checked. CHO needed by the patients to prevent hypoglycemia decreased as the time elapsed from insulin administration increased, amounting to 0.63 ± 0.30, 0.44 ± 0.32, 0.28 ± 0.24, and 0.14 ± 0.18 g/kg after 1, 2.5, 4, and 5.5 hours, respectively. Total glucose requirement during moderate exercise (sum of alimentary and extracellular source) was correlated (r = 0.739, P < .001) to plasma insulin concentration, but not with fitness level. Time elapsed from last insulin dose is not a factor influencing the risk of hypoglycemia during exercise when a proportional, appropriate amount of CHO is ingested.

Section snippets

Subjects

Twelve type 1 diabetic patients (6 men and 6 women) age 18 to 45 years volunteered to be subjects. A control group of 12 well-matched healthy subjects (6 males and 6 females) was also studied. All subjects were informed of the nature, purpose, and possible risks involved in the study before giving their voluntary consent to participate. The study was approved by the local ethical committee and was conducted according to the principles expressed in the Declaration of Helsinki.

Patients were

Results

According to the forms filled in by the subjects, all diabetic volunteers were compliant to the request of abstaining from exercise the day before the trials and maintaining the same diet and insulin routine the day before and after the experimental sessions.

Discussion

The experimental protocol followed for the present work allowed us to determine the amount of CHO needed by type 1 diabetic patients to prevent hypoglycemia during exercise.

Acknowledgements

We thank Dr E. Belluco, Dr L. Aita, and Dr F. Reccardini for their help during the experimental sessions and Professor P.E. di Prampero and Professor S. Del Prato for helpful discussion.

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    Supported by funds from the Ministero dell’Università e della Ricerca Scientifica (MURST 60%, main investigator L. Cattin).

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