Insulin, a hormone, regulates blood sugar levels. For individuals managing diabetes, insulin therapy is often a daily necessity. Maintaining the medication’s effectiveness relies on proper handling and storage.
Understanding Insulin Stability
Insulin is a protein sensitive to environmental factors. Extreme temperatures, both excessive heat and freezing, can cause the protein to break down or change its shape, a process known as denaturation. This alteration renders the insulin less effective or even completely inactive, compromising its ability to manage blood sugar.
Direct sunlight and vigorous agitation also contribute to insulin degradation. Light accelerates chemical reactions, while excessive shaking can cause protein molecules to aggregate, forming clumps. These physical changes reduce the insulin’s potency and can make injections more difficult. Proper storage protects its delicate protein structure to ensure it remains therapeutically active.
How Long Insulin Remains Potent Unrefrigerated
Once a vial or pen is opened or removed from refrigeration for daily use, storage guidelines change significantly. Most insulins can then be kept at room temperature, generally defined as 15°C to 30°C (59°F to 86°F), for a specific period.
For many common insulin formulations, this unrefrigerated period typically lasts up to 28 days. Variations exist depending on the specific insulin type and manufacturer. Some insulins might remain stable for shorter durations, such as 14 days, while others, like insulin degludec (Tresiba), can be stable for up to 8 weeks, and Toujeo for 42 days. Insulin used in pump reservoirs has an even shorter stability period, usually requiring replacement every 48 to 72 hours. Always consult the manufacturer’s instructions for the precise temperature range and duration for your particular insulin product.
Recognizing Compromised Insulin and Safe Disposal
Identifying insulin that has lost potency due to improper storage is important for patient safety. Visual changes can indicate damage: clear insulin should remain clear, without cloudiness, discoloration, or particles. Cloudy insulins, such as NPH, should appear uniformly milky after gentle rolling, without clumping, frosting on the vial, or fine particles sticking to the glass.
Even if no visible changes are apparent, insulin subjected to extreme temperatures (e.g., freezing or prolonged heat) or exceeding its unrefrigerated use-by date should be discarded. Using compromised insulin can lead to unpredictable blood sugar levels and may not provide the necessary therapeutic effect.
For disposal, used needles and syringes (sharps) must be immediately placed in an FDA-cleared sharps disposal container. If a commercial container is unavailable, a heavy-duty plastic container with a tight, puncture-resistant lid, like a laundry detergent bottle, can serve as a temporary alternative, labeled clearly as “Sharps Container” and “Do Not Recycle.” Full sharps containers should be disposed of according to local regulations, which often involve drop-off sites or mail-back programs, and should never be put directly into household trash or recycling unless specifically permitted by local guidelines.
Empty insulin vials, cartridges, and pens (without the needle attached) can typically be disposed of in regular household trash and are generally not recyclable. Unused or expired liquid insulin should not be flushed down the toilet; instead, it can be mixed with an unappealing substance like coffee grounds or kitty litter, sealed in a bag or container, and placed in the trash, or returned to a drug take-back program if available.
Best Practices for Insulin Storage and Travel
Unopened insulin should be refrigerated between 2°C and 8°C (36°F and 46°F), away from the freezer compartment to prevent accidental freezing. For insulin in use, keeping it at room temperature, typically between 15°C and 30°C (59°F and 86°F), is acceptable and can make injections more comfortable. Protect in-use insulin from direct sunlight and extreme heat sources, such as car dashboards or window sills.
When traveling, meticulous planning for insulin storage is advisable. Always pack insulin in your carry-on luggage when flying, as checked baggage can be exposed to freezing temperatures in the cargo hold. Using insulated bags or coolers with gel packs helps maintain a stable temperature; avoid direct contact between insulin and ice packs.
Bringing double the amount of insulin and supplies needed for your trip provides a buffer against unexpected delays or losses. Informing airport security about your medical supplies can also help facilitate a smoother screening process.