At over 8,800 meters high, Mount Everest is the highest mountain on Earth, with oxygen levels on the summit a third of those at sea level. Though the inhospitable environment of the mountain is not ideal for conducting studies, researchers have used the high altitude to study how low oxygen levels in the body - known as hypoxia - are linked to the development of insulin resistance.
Results of the study, conducted by researchers at the University of Southampton and University College London (UCL) in the UK, are published in the journal PLOS One.
Their findings come from a 2007 study, called Caudwell Xtreme Everest. This research group is comprised of intensive care doctors, nurses and scientists who conduct experiments on themselves and other volunteers at high altitudes.
The team says they have gained a better understanding of the molecular process involved when some people get type 2 diabetes. When cells fail to respond to insulin in the body, this is known as insulin resistance.
Because insulin helps the body regulate sugar levels, if this process is faulty, then too much sugar in the body can be toxic, leading to type 2 diabetes.
According to the Centers for Disease Control and Prevention (CDC), type 2 diabetes accounts for 90-95% of diabetes cases in the US. It can be prevented through healthy food choices, physical activity and weight loss, however, once it sets in, insulin or oral medication may be required.
Long-term hypoxia exposure yields increased insulin resistance markers
Pictured here, Dr. Sundeep Dhillon gets tested on an exercise bike at Everest Base Camp.
Image credit: Caudwell Xtreme Everest
To further investigate the mechanisms behind this disease, 24 individuals went to Mount Everest Base Camp - at an altitude of 5,300 meters - and had glucose control assessments, body weight changes and inflammation biomarkers measured.
While half of this group stayed at Base Camp, the other half climbed the mountain to the summit, at 8,848 meters. At week 6 and 8 of the journey, measurements were taken in each group.
"The environment in which we work at altitude means that our equipment and investigators are pushed to their limits," Dr. Daniel Martin told Medical News Today.
He is a senior lecturer and honorary consultant at UCL Division of Surgery and Interventional Science, as well as the director of UCL CASE Medicine.
At the end of the study period, the researchers found that several insulin resistance markers were increased after long-term exposure to hypoxia at high altitude.
The team says this change was connected to increased blood levels of markers of inflammation and oxidative stress.
Prof. Mike Grocott, professor at the University of Southampton and co-founder of UCL CASE Medicine, says their findings have given them a better understanding of insulin resistance:
"Fat tissue in obese people is believed to exist in a chronic state of mild hypoxia because the small blood vessels are unable to supply sufficient oxygen to fat tissue."
"Our study was unique in that it enabled us to see things in healthy people at altitude that which we might normally only see in obese people at sea level. The results suggest possible interventions to reduce progression towards full-blown diabetes, including measures to reduce oxidative stress and inflammation in the body."
'Data could one day change how critically ill patients are treated'
Speaking with Medical News Today, Dr. Martin explained that understanding the pathways leading to insulin resistance could one day lead to pharmacological targets.
Fast facts about diabetes
- In the US, 25.8 million people have diabetes, 7 million of whom are undiagnosed.
- If trends continue, by 2050, 1 in 3 adults will have diabetes.
- In adults, diabetes is the leading cause of new cases of blindness, kidney failure and amputations not related to accidents.
"Drugs that act to damp down or alter oxidative stress and/or inflammation could have a beneficial effect on insulin metabolism," he said.
Alongside their findings, the team was also able to record the first ever measurement of the oxygen levels of human blood at 8,400 meters.
This is all part of a larger research project into hypoxia and human capability at high altitudes, which the team says aims to improve care for critically ill patients with hypoxia.
Dr. Martin explained to us some of the obstacles he and his team faced:
"The temperature at Everest base camp fluctuates markedly during the day, from a pleasant climate at lunchtime to way below zero by nightfall. The thin air at altitude makes working very tiring, and the long hours we put in every day in the high altitude laboratories is hard on our team."
Still, he said their work is very rewarding, especially "knowing that within that data may be findings that one day could change the way we treat critically ill patients at sea level."