Insulin is a hormone crucial for managing blood glucose levels, especially for individuals with diabetes. It transports sugar from the bloodstream into cells for energy or storage. Proper storage is essential for maintaining insulin’s effectiveness, as this delicate protein degrades under unsuitable conditions.
Understanding Room Temperature Stability
Once removed from refrigeration and put into use, most insulin products can be stored at “room temperature” for a specific period. Room temperature generally refers to a range between 59°F and 86°F (15°C to 30°C). Many manufacturers indicate that insulin in vials, pre-filled pens, or cartridges remains stable for up to 28 days under these conditions.
Specific products have varying guidelines; always check the manufacturer’s instructions. For instance, Toujeo can be stable for up to 42 days, and Tresiba may last up to eight weeks at room temperature. Insulin in pump reservoirs often has a shorter in-use duration, typically requiring discard after 48 to 72 hours, or sooner if exposed to temperatures above 98.6°F (37°C).
While unopened insulin is best kept refrigerated, insulin currently in use does not need to be kept cold. Injecting cold insulin can cause discomfort, making room temperature storage more practical for daily use. Once a vial or pen is opened, its stability at room temperature begins, and it should be discarded after the recommended in-use period, even if some insulin remains.
Factors Influencing Insulin Degradation
Beyond room temperature duration, several environmental factors can cause insulin to lose potency before its expiration date. Temperature extremes, including excessive heat and freezing, significantly impact insulin’s protein structure. High temperatures accelerate insulin’s chemical degradation, reducing its ability to regulate blood sugar effectively.
Conversely, freezing temperatures can irreversibly alter insulin’s molecular structure, rendering it ineffective even if it thaws afterward. Avoid placing insulin near cooling elements in a refrigerator where it might accidentally freeze. Exposure to direct sunlight or strong artificial light also contributes to insulin degradation.
Physical agitation, like vigorous shaking, can also damage the insulin protein, leading to a loss of strength and visible clumps or particles. Protecting insulin from these stresses preserves its integrity and therapeutic effect.
Recognizing Impaired Insulin
Visually inspecting insulin before each use can help identify potential degradation. Clear insulins, like regular insulin, should remain so; cloudiness, discoloration, or solid particles indicate spoilage. For insulins that are naturally cloudy, such as NPH, look for changes like frosting on the bottle or clumping that does not disappear with gentle mixing.
If insulin appears yellowish or brownish, or if it contains flakes or crystals that settle at the bottom, it should not be used. Even without obvious visual changes, unexpectedly high blood sugar levels despite proper dosing could signal that the insulin has lost potency due to improper storage. Using degraded insulin can lead to uncontrolled blood sugar levels, which poses health risks.
Optimal Storage Practices
Unopened insulin should be refrigerated at 36°F to 46°F (2°C to 8°C) to maintain potency until its expiration date. Never freeze insulin, as this permanently damages it.
For insulin currently in use, it is generally recommended to store it at room temperature, typically below 86°F (30°C), within its specified in-use period, often 28 days. Once an insulin pen is opened, it should not be returned to the refrigerator. Keep insulin away from direct heat sources, such as stoves or car dashboards, and out of direct sunlight.
When traveling, carry insulin in hand luggage, especially when flying, to avoid extreme cargo temperatures. An insulated bag or travel cooler can help maintain temperature, but avoid direct contact with ice packs to prevent freezing. Always check expiration dates and note the opening date to ensure use within the recommended timeframe.