The body’s management of blood sugar is significantly altered when ascending to elevations typically above 8,000 feet. For individuals managing diabetes, understanding this physiological shift is important for maintaining health and safety. The initial ascent often triggers one set of biological reactions, while prolonged stays lead to different metabolic adjustments.
The Role of Hypoxia and Stress Hormones
The reduction in available oxygen, known as hypoxia, is the primary driver of changes in glucose metabolism at high altitudes. Upon rapid ascent, the body perceives the low oxygen environment as a severe physical stressor. This stress immediately activates the sympathetic nervous system, initiating a “fight or flight” response.
This activation results in the rapid release of counter-regulatory hormones, mainly cortisol and epinephrine (adrenaline), into the bloodstream. These hormones flood the body with quick energy to deal with the perceived threat. Epinephrine stimulates the liver to break down stored glycogen into glucose (glycogenolysis).
Cortisol also contributes by promoting gluconeogenesis, the creation of new glucose from non-carbohydrate sources like protein. Both cortisol and epinephrine can induce temporary insulin resistance, making existing insulin less effective at moving glucose out of the blood and into the cells. The combined effect of increased glucose production and diminished insulin action often results in a spike in blood sugar levels, or hyperglycemia, during the initial hours and days at altitude.
Acute vs. Sustained Effects on Glucose Levels
The initial, acute phase of high-altitude exposure, generally spanning the first 24 to 72 hours, is characterized by the dominance of the stress response. During this time, the hormonal surge causes significant volatility, often leading to elevated blood glucose levels and a greater challenge in maintaining stable control. This is frequently complicated by the onset of acute mountain sickness, which includes symptoms like nausea, headache, and a loss of appetite.
The physical symptoms of altitude sickness can mimic or obscure the signs of hypoglycemia, making it difficult for an individual to distinguish between the two without testing. A loss of appetite due to nausea can lead to reduced food intake, indirectly increasing the risk of low blood sugar, despite the concurrent stress-induced insulin resistance.
As the body remains at high altitude and begins the process of acclimatization, the metabolic picture gradually shifts. After this initial period of volatility, the body often exhibits enhanced insulin sensitivity. Chronic hypoxia may induce metabolic changes that improve glucose utilization, sometimes resulting in a lower baseline fasting blood sugar level compared to sea level. This sustained effect means that individuals may require less medication or insulin over time, which increases the potential for unexpected hypoglycemia, especially when combined with increased physical activity.
Essential Adjustments for Managing Diabetes in High-Altitude Settings
Effective diabetes management at high altitude necessitates a proactive approach, beginning with frequent blood glucose monitoring. Individuals should check their blood sugar levels more often than usual, particularly during the first few days and overnight, to capture the unpredictable swings caused by the acute stress response. Using a continuous glucose monitor (CGM) can be helpful for tracking trends, but manual testing is still recommended to confirm readings, especially in extreme temperatures.
Hydration is a considerable factor, as the dry air and increased respiration at altitude lead to a faster rate of fluid loss. Dehydration can worsen hyperglycemia by concentrating glucose in the bloodstream, so maintaining a high fluid intake, including water and electrolyte-rich drinks, is advised. Travelers should consult with their healthcare provider regarding potential adjustments to insulin doses or oral diabetes medications.
Due to the later-stage increase in insulin sensitivity, basal insulin rates or the dosage of certain oral medications may need to be reduced after the initial acute phase to prevent hypoglycemia.
Individuals must also be mindful that altitude and cold temperatures can affect the functionality of diabetes equipment. Insulin pumps, glucose meters, and test strips should be protected from freezing temperatures by being stored close to the body, such as in an interior pocket. Carrying extra supplies, including low-blood-sugar treatments and ketone testing strips, is a necessary precaution given the remote nature of many high-altitude locations.