medwireNews: Blood glucose falls further when people with type 1 diabetes run than when they cycle, show the findings of a systematic review and meta-analysis.
“When preparing for exercise, regularly physically active individuals with type 1 diabetes must be aware of what type of endurance exercise, intensity and duration will be conducted to avoid [exercise-induced hypoglycemia] and to safely conduct physical exercise,” say the researchers.
“Recommendations around physical exercise should be given according to the amount of musculature used during endurance exercise and not just by its type.”
Of the 69 articles included in the analysis, 49 examined cycling in participants with type 1 diabetes ranging from 10 to 65 years of age for a duration ranging from 10 minutes to 3 hours and the other 20 studies looked at running in people aged from 12 to 56 years for between 30 and 180 minutes.
The pooled average blood glucose reduction was 2.7 mmol/L for the cycling studies but a considerably larger 4.1 mmol/L for the running studies.
“Our hypothesis that the whole-body movement running, in comparison to cycling, utilizes more energy in form of glucose from the blood stream is therefore confirmed,” write Othmar Moser (University Bayreuth, Germany) and co-researchers in Diabetic Medicine.
For both exercise types, a longer duration of exercise led to a larger reduction in blood glucose levels. Also, higher-intensity exercise tended to be associated with a larger blood glucose reduction, particularly in the running studies, where the average reductions were 2.7, 3.3, and 4.6 mmol/L with low-, moderate-, and high-intensity exercise, respectively.
In the cycling studies, there was no significant difference in the reduction that occurred with continuous versus high-intensity interval exercise, but there was a clear difference in the running studies, at an average of 4.4 versus 1.1 mmol/L.
An “unexpected” finding was that reducing insulin prior to exercise resulted in a larger blood glucose increase than not doing so in the pooled analysis. The researchers suggest this could be due to variable approaches among the studies to the amount and type of carbohydrates consumed before exercise, which they were unable to account for in their analysis.
The team calls for future studies to consider “the exact monitoring of pre-exercise carbohydrate consumption and insulin management and additionally the post-exercise glucose management.”
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