High-Altitude Exercise May Harm Blood Sugar Control in Type 1 Diabetes

By Megan Brooks

January 04, 2022

NEW YORK (Reuters Health) - People with type 1 diabetes mellitus (T1DM) may need to monitor their blood sugar more closely when participating in high-altitude activities such as hiking or skiing, according to results of a small study that found a risk of low blood sugar with high-altitude physical exertion.

The findings should "raise awareness" about the potential complications individuals with T1DM might experience when exercising at high altitudes, Cory Dugan of the School of Human Sciences, University of Western Australia, in Crawley, told Reuters Health by email.

"More care should be taken to ensure the safety of all individuals with diabetes when traveling or exercising at high altitudes," said Dugan.

Current exercise guidelines for people with T1DM do not consider the impact that high altitude may have on blood glucose levels during exercise, Dugan and colleagues note in the Journal of Clinical Endocrinology & Metabolism.

They studied seven people with T1DM, measuring blood glucose levels before, during and after two indoor cycling sessions that mimicked conditions at sea level (normal oxygen) and conditions at high-altitude (low oxygen).

Early during exercise (less than 30 minutes), there was no fall in blood glucose level in either condition.

However, after one hour of exercise at a simulated 4,200 meters (about half the height of Mount Everest) and during recovery, blood sugar levels were significantly lower under the hypoxic condition compared to both pre-exercise levels (P=0.008) and the normal oxygen condition (P=0.027).

Exercise in both conditions led to a significant rise in carbohydrate oxidation rates, which returned to baseline levels after exercise. Before, during and after exercise, carbohydrate oxidation rates were higher under the high-altitude (hypoxic) condition.

These findings suggest physical exertion at high altitude may increase the risk of hypoglycemia in people with T1DM.

Dugan told Reuters Health that "environmental conditions, such as high altitude, need to be considered when forming guidelines concerning glucoregulation during both rest and exercise."

He cautioned that it would not be appropriate to extrapolate the findings to other populations, including individuals with type 2 diabetes.

SOURCE: https://bit.ly/3EwxMnY Journal of Clinical Endocrinology & Metabolism, online December 22, 2021.

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