Insulin is a medication used to manage blood glucose levels in individuals with diabetes. Proper storage helps maintain its potency. Understanding how to store insulin correctly, both before and after opening, is important for ensuring it works as intended.
General Insulin Storage Guidelines
Unopened insulin products should be stored in a refrigerator to maintain potency until expiration. The recommended temperature range is between 36°F and 46°F (2°C and 8°C). This cool environment helps prevent degradation.
Avoid freezing insulin, as this can damage its structure and render it ineffective. If insulin freezes, it should not be used. Protect insulin from extreme heat and direct sunlight, which can also cause it to lose effectiveness. Store insulin away from the freezer compartment or cooling elements to prevent accidental freezing.
Room Temperature Stability of Opened Insulin
Once opened, insulin can typically be kept at room temperature for a specific duration. This room temperature range is between 59°F and 86°F (15°C and 30°C). Do not return opened insulin to the refrigerator.
The exact duration varies by insulin type and manufacturer. Many insulin vials, pens, and cartridges are stable for up to 28 days. For example, insulin glargine (Basaglar), insulin lispro (Humalog), and insulin aspart (Novolog) have a 28-day stability period.
Some insulins have different durations; for instance, insulin degludec (Tresiba) pens and vials can be stable for up to 56 days, while insulin detemir (Levemir) is stable for 42 days. Humulin R vials are good for 31 days once opened. For insulin used in pump devices, the insulin within the infusion set should be discarded after 48 hours, or sooner if exposed to temperatures exceeding 98.6°F (37°C). Always consult the specific product’s instructions for accurate information regarding in-use stability.
Identifying and Handling Compromised Insulin
Visual inspection is a primary method for identifying insulin that may be compromised and no longer effective. Healthy insulin should appear clear and colorless, similar to water, with the exception of intermediate-acting insulins like Humulin N and Novolin N, which are normally cloudy or milky. Any changes in appearance, such as cloudiness (for clear insulins), discoloration, the presence of clumps, particles, or “frosting” inside the vial, indicate that the insulin has likely degraded.
Other signs of compromised insulin include an unusual texture or the formation of crystals. If any of these visual changes are observed, the insulin should not be used, regardless of how long it has been out of the refrigerator or its stated expiration date. Using degraded insulin can lead to unpredictable blood sugar levels, which can be dangerous.
When insulin is suspected of being compromised, it should be safely discarded. This typically involves disposing of it according to local guidelines for medical waste. It is advisable to contact a healthcare provider or pharmacist for specific disposal instructions and to discuss obtaining a new, effective supply of insulin.