High Altitude Exercise Linked to Lowered Blood Glucose

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High Altitude Exercise Linked to Lowered Blood Glucose

Exercising at high altitudes might cause a precarious lowering of blood sugar in people with type 1 diabetes, reports a new study from researchers at the University of Western Australia. The research was published in the Journal of Clinical Endocrinology & Metabolism.

People with type 1 diabetes have proven themselves capable of achieving impressive feats at high altitudes. They have successfully gone skydiving, for example, and in 2006 an adventurer named Will Cross became the first person with type 1 diabetes to climb Mount Everest. Several studies have investigated the effect of exercise on blood glucose control in those with diabetes, but little scientific research has been done on how high-altitude exertion might affect people with type 1, especially when it comes to blood sugar levels. For that reason a team of researchers led by Cory Dugan, BSc, of the Department of Exercise Physiology and Biochemistry at the University of Western Australia in Perth, decided to subject the matter to scientific analysis.

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Between January and September 2019 the researchers recruited seven adults with type 1 diabetes and no history of respiratory illness with the aim of comparing how well they were able to exercise at sea level and at high altitude. For the purposes of the study they defined high altitude as 4,200 meters, or 13,780 feet, which is about the height of Mount Whitney in California. The investigators, however, did not transport their volunteers to the top of a mountain that tall, which would have been impossible in Australia anyhow, where the highest peak is only 2,228 meters (7,310 feet) high. Instead, they used what’s known as a simulated hypoxic condition — that is, in the lab they created an environment in which the oxygen levels in the subjects’ blood were lowered to those encountered at high altitudes.

The subjects were first given a session in which they got acquainted with the equipment and during which they had various noninvasive measures taken, such as height and weight, and underwent an exercise test to measure oxygen consumption. This familiarization phase was followed by two exercise periods. These sessions each consisted of one hour of exercise on a cycle ergometer, which is a common instrument for measuring the health status of the heart and lungs. It’s a special type of stationary bicycle that’s connected to a device that measures the user’s work performance. The first exercise session was done at a simulated sea level (0 meters) in which the air was 27% oxygen. The second was done at a simulated high altitude (4,200 meters or 13,780 feet) in which the air was 12.1% oxygen. For both sessions the researchers took blood samples before, during, and after exercise. They measured glucose, lactate, and insulin while also collecting respiratory gases.

High-altitude exercise linked to lower blood glucose in type 1

As the researchers expected, the heart and respiration rates of the exercisers were higher in the high-altitude situation. But the researchers also found that high-altitude exercise increased the rate of carbohydrate oxidation and lactate production while at the same time lowering the blood glucose level. Hypoglycemia, or blood glucose below target levels, can be dangerous. A mild case can cause headache, sweating, trembling, and a throbbing heartbeat, but if the glucose level gets exceptionally low a person can pass out or suffer a seizure. Eventually hypoglycemia can result in coma or death.

The researchers acknowledged that the number of participants in the study was small and commented that future studies will be needed to uncover the actual physical processes that cause the blood glucose drop. In the meantime, however, they wrote, “We ask that future guidelines consider these findings to increase the safety of people with Type 1 diabetes when traveling from low to high altitude areas like the mountains without any acclimatization.”

Want to learn more about blood glucose management? See our “Blood Sugar Chart,” then read “Blood Sugar Monitoring: When to Check and Why” and “Strike the Spike II: How to Manage High Blood Glucose After Meals.”

Joseph Gustaitis

Joseph Gustaitis

Joseph Gustaitis on social media

A freelance writer and editor based in the Chicago area, Gustaitis has a degree in journalism from Columbia University. He has decades of experience writing about diabetes and related health conditions and interviewing healthcare experts.

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