Why Do Diabetic Test Strips Expire?

Monitoring and controlling your diabetic symptoms can cause a huge dent in your budget. A piece of the diabetic test strip can cost up to $2, and if you’re buying a box of 50 at a time, you sure know that the costs add up. Considering how expensive it is to be diabetic, you would want to make the most out of your supplies. 

There are varying opinions as to whether it is okay to use expired diabetic test strips or not; but before going into that, let’s discuss how these test strips work and why they expire.

How do diabetic test strips work?

To understand why diabetic test strips expire, we have to know how they work first. These strips are made up of several layers. The first layer soaks up your blood. The second layer serves as a filter that will channel your blood to the reaction layer, which is made up of three components: an enzyme that reacts with the glucose in your blood, a chemical that speeds electrons through the circuit for an accurate reading, and a solution of chemicals that preserve the enzyme and mediator chemicals. This is also what you call the “chemistry strip.” The bottom layer has your circuit, usually coated in palladium and gold, which transfers the reaction electrons to your glucose meter to get you your reading. 

Why do diabetic test strips expire?

Every test strip has a “living” enzyme in it, which means that through time, this will die or disintegrate, leaving the test strip ineffective and the reading inaccurate. When the enzymes are no longer able to attach themselves to the glucose in your blood or pull off the electrons in your sugar, the risk of getting inaccurate results is high. 

It is then very important to heed the expiration dates indicated in diabetic test strip bottles. However, some may argue that these expiration dates could be a way for companies to make more money by making patients throw away their supplies earlier than they are supposed to. While it is undeniable that it is, after all, a business, there could be more to it than that. Manufacturers should ensure that the products perform as well as the label suggests, and expiration dates serve as protection on their end. If they move the expiration dates back, it would only take one inaccurate test strip to cost them a lawsuit. 

Can you still use expired diabetes test strips?

The strips are only effective as long as the enzymes in them are active. Once you have opened a bottle of test strips, you are exposing the strips to humidity and the other chemicals present in the atmosphere, thus hastening the enzymes’ disintegration. Make sure to always close the bottle tightly after each use to ensure that the strips remain good and intact for a while. Brands differ in the duration of effectiveness. For example, OneTouch test strips are good for six months after first opening the bottle, or until the expiration date, whichever comes first. Nipro Diagnostics test strips, on the other hand, are good for 120 days after opening the bottle or until the expiration date. You may ask, “how about unopened bottles?” If the bottle is unopened and has been stored properly, you can still use the strips until a year after the expiration date.

Do take note that these are just guides. Keep in mind that there are risks involved with using expired diabetic test strips. While you might be saving a few dollars by stretching out your stash for a few days or weeks, a trip to the emergency room due to a complication caused by an inaccurate reading will definitely cost you more.