Insulin serves as a medication for individuals managing diabetes, regulating blood sugar levels. Its effectiveness relies on maintaining specific storage conditions, particularly temperature. Exposure to excessive heat can alter insulin’s delicate structure and function, potentially rendering it ineffective.
How Heat Affects Insulin
Insulin is a protein, and like many proteins, its three-dimensional structure is susceptible to changes when exposed to elevated temperatures. This process, known as denaturation, involves the unraveling or breaking down of the protein’s complex folds. When insulin denatures, its specific molecular shape changes, which prevents it from properly binding to insulin receptors on cells in the body. This structural alteration directly impairs its ability to facilitate glucose uptake from the bloodstream. This degradation is irreversible; once denatured by heat, insulin cannot regain its original, functional form.
Consequences of Using Compromised Insulin
Injecting insulin that has lost its potency due to heat exposure can lead to uncontrolled high blood sugar, a condition known as hyperglycemia. The compromised insulin cannot effectively lower glucose levels. Immediate symptoms of hyperglycemia may include increased thirst, frequent urination, and feelings of fatigue. If left unaddressed, prolonged hyperglycemia can lead to more severe short-term complications, such as diabetic ketoacidosis.
Identifying Damaged Insulin
Observing the insulin’s appearance can sometimes indicate heat damage, though visual changes are not always present. Clear insulin, such as regular or rapid-acting types, might appear cloudy, discolored, or contain clumps or crystals if compromised. Cloudy insulins, like NPH, may show a frosted appearance or have particles that do not readily mix back into suspension. Even without visible changes, a noticeable lack of effectiveness in lowering blood sugar after suspected heat exposure is a strong indicator of damage.
Preventing Heat Damage and Next Steps
Preventing insulin from getting too warm involves careful storage practices. Unopened insulin vials or pens should be stored in a refrigerator, typically between 36°F and 46°F (2°C and 8°C). Once opened, many insulins can be stored at room temperature, generally between 59°F and 86°F (15°C and 30°C), for up to 28 days, depending on the product. It is important to avoid direct sunlight, hot cars, or leaving insulin near heat sources like radiators.
If insulin is suspected to have been exposed to excessive heat, it should be discarded. After discarding, it is advisable to monitor blood sugar levels more frequently and contact a healthcare provider for guidance and replacement medication.