Type 1 diabetes (T1D) is an autoimmune condition where the pancreas produces little to no insulin. Traveling to or living at higher elevations introduces environmental stressors that can significantly complicate T1D management. Altitude changes affect the body’s internal chemistry and the performance of diabetes technology, creating an unstable environment for glucose control.
Physiological Impact on Glucose Regulation
The primary physiological challenge at high altitude is hypoxia, a state of reduced oxygen availability, which the body interprets as intense stress. In response to this stress, the body releases counter-regulatory hormones, mainly cortisol and adrenaline (epinephrine), to help cope with the lower oxygen levels. These hormones work to increase the availability of energy, which directly interferes with glucose homeostasis.
Cortisol stimulates gluconeogenesis, the process where the liver produces new glucose from non-carbohydrate sources, leading to an increase in circulating blood sugar. Simultaneously, both cortisol and adrenaline contribute to insulin resistance, making the body’s cells less responsive to the insulin that is administered. This combination of increased glucose production and decreased insulin effectiveness often results in hyperglycemia, or high blood sugar, especially upon initial ascent.
This initial hyperglycemic effect can be temporary as the body begins to acclimatize. When high altitude exposure is combined with physical activity, such as hiking or climbing, the risk profile shifts significantly toward hypoglycemia. Exercise at altitude increases the muscles’ demand for glucose, leading to a more rapid decline in blood glucose levels during and after activity. Individuals with T1D may face a rapid “rollercoaster” effect, starting with high blood sugar from stress hormones and then potentially dropping low due to exertion.
Effects on Insulin Stability and Delivery Devices
Beyond the body’s internal response, the external environment at high altitude presents practical challenges for diabetes supplies and equipment. Insulin itself is highly sensitive to temperature extremes, and the cold temperatures often encountered at elevation can compromise its potency or even cause it to freeze. Unopened insulin can typically be kept unrefrigerated between 59°F and 86°F (15°C and 30°C) for several weeks, but temperatures outside this range risk physical degradation and a loss of bioactivity.
Insulin pumps are particularly susceptible to changes in atmospheric pressure, which can lead to unintended insulin delivery. As pressure drops during ascent (or during commercial airline travel), air bubbles already present in the insulin cartridge or tubing will expand according to Boyle’s Law. This expansion displaces the insulin, causing a small, unintended bolus to be delivered, which poses a risk of hypoglycemia.
The opposite effect occurs during descent, where bubbles contract and can lead to under-delivery and potential hyperglycemia. Continuous glucose monitors (CGMs) and traditional blood glucose meters also have operating limits. Many meters lose accuracy or fail to function outside of specific temperature ranges, typically between 50°F and 104°F (10°C and 40°C).
Essential Management Adjustments for Altitude
Managing T1D at high altitude requires proactive planning and frequent adjustments. Consulting with a healthcare provider before travel is necessary to discuss potential insulin dose modifications and to prepare for the trip.
Increased monitoring frequency is non-negotiable, especially during the initial days of ascent or periods of activity. This vigilance helps to distinguish between the symptoms of altitude sickness—such as nausea and exhaustion—and the similar symptoms of hypoglycemia. Carrying fast-acting carbohydrates is necessary for immediate treatment of lows, as the body’s ability to absorb food can be altered at extreme elevations.
For those using insulin pumps, momentarily disconnecting the pump during rapid ascent and manually priming the tubing removes any air bubbles that may have formed. Protecting all diabetes supplies from temperature extremes is important; insulin and devices should be kept close to the body in an interior pocket to prevent freezing or overheating.
It is generally recommended to start with conservative insulin dosing, as the fluctuating effects of altitude stress and physical activity make prediction difficult. Adequate hydration is also important, as dehydration is a common risk at altitude and can worsen glucose control, increasing the danger of developing diabetic ketoacidosis (DKA).