Insulin pens are a common and effective tool for managing diabetes. It is important to know that insulin pens do expire, which is a serious safety consideration for anyone using these devices to manage their blood sugar levels.
Identifying Expiration Dates
Insulin pens have two important expiration dates. The manufacturer’s expiration date for an unopened pen is found on the pen label and its packaging, applying when stored correctly, usually refrigerated. Once an insulin pen is opened, a shorter “in-use” expiration period begins. Most pens are good for about 28 days after opening, though this can vary by brand and type of insulin, with some lasting from 14 to 56 days. It is helpful to mark the date of opening on the pen to ensure it is discarded within its “in-use” period.
The Science Behind Insulin Expiration
Insulin is a protein, and like all proteins, it is susceptible to degradation over time. This degradation leads to a loss of potency, meaning the insulin becomes less effective at lowering blood sugar. Factors such as exposure to light, extreme temperatures, and physical agitation can accelerate this breakdown process. The insulin molecule can undergo irreversible changes, including protein clumping, which reduces its ability to bind to receptors and promote glucose uptake. Additionally, the sterility of the insulin may be compromised over time, increasing the risk of contamination.
Consequences of Using Expired Insulin
Using expired insulin poses significant health risks because its potency is reduced. This diminished effectiveness can lead to uncontrolled high blood sugar, known as hyperglycemia. Symptoms of hyperglycemia include increased thirst, frequent urination, fatigue, and blurred vision. If left unaddressed, it can result in more severe complications like diabetic ketoacidosis (DKA), particularly for individuals with type 1 diabetes. DKA is a serious condition where the body produces harmful ketones. The primary danger is the lack of proper blood sugar control, which can lead to both acute and long-term health issues, including nerve and kidney damage.
Proper Care for Insulin Pens
Proper storage and handling are important to maintain insulin’s effectiveness. Unopened pens should be refrigerated (2°C-8°C / 36°F-46°F) until use.
Once opened, store at room temperature (15°C-30°C / 59°F-86°F), protected from direct sunlight or extreme heat. Never freeze insulin, as it destroys its structure and renders it ineffective.
Additionally, pens should not be shaken vigorously, and the cap should be replaced after each use to protect the insulin from light exposure. Dispose of used or expired pens and needles in a sharps container for safety.