Do Blood Sugar Test Strips Expire?

Diabetes mellitus is one of the most common chronic disorders, affecting 422 million people worldwide [1]. In America, more than 133 million people are living with this disorder [2]. As the disease progresses, it can cause vision loss, heart disease, and kidney disease.

Diabetes is a disorder of glucose metabolism. Our body is unable to turn glucose into energy. This can be because of reduced insulin production (type 1 diabetes mellitus) or resistance to the effect of insulin (type 2 diabetes mellitus, T2DM). T2DM is more common. The body cannot use glucose in both types, and blood levels of this sugar are abnormally high.

There is no cure for diabetes. Managing this disorder needs discipline in diet and exercise, regular blood sugar level testing, and expert treatment. It is entirely possible for us to control diabetes and live a healthy, active life.

Since it is a chronic, lifelong disorder, it is essential to manage a large part of it ourselves. Doing so requires a way to measure blood levels of glucose to assess both the disease and the efficacy of treatment. Frequent measurement of blood sugar is crucial for the effective management of diabetes, but going to a laboratory so often is difficult. Glucose test strips offer a simple way to measure our blood glucose levels at home.

How Do Glucose Test Strips Work?

Blood glucose test strips are narrow plastic strips carrying enzymes and chemicals. Modern glucose test strips contain the enzyme glucose oxidase or glucose dehydrogenase. When a blood drop is applied to this, the enzyme turns glucose into D-gluconic acid and hydrogen peroxide. This reaction generates an electrical current that is measured by a glucometer, showing us the glucose level [3].

Older glucose test strips used these enzymes with horseradish peroxidase and 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS). When blood was applied, the chemical reaction generated a blue-green colored chemical. Measuring this color gave a blood glucose level reading [4]. Such machines and strips are not in use now.

The American Diabetic Association recommends the following blood sugar levels for those of us living with diabetes [5]:

• Before a meal (fasting or pre-prandial blood glucose: 80 to 130 milligrams/deciliter (4.44 to 7.22 millimoles/liter)
• One to two hours after a meal (post-prandial blood glucose: Less than 180 milligrams/deciliter (10 millimoles/liter)

Levels higher than this indicate diabetes is not well-controlled. A single high reading should not alarm us. However, if the blood sugar levels are higher than expected frequently, we should talk to our doctor. They may suggest a change in the dosage of insulin or other antidiabetic medicines.

Do Blood Sugar Test Strips Expire?

Yes, blood glucose test strips can be used for a finite period. They depend on sensitive chemicals and processes to generate precise test results. The chemicals are complex molecules and require particular conditions of moisture and temperature for their stability.

Even under appropriate conditions, they deteriorate over time. Though test strips can be used for some years after manufacture, they become less reliable within months once the packaging has been opened.

Proper storage is crucial to obtaining accurate results with glucose test strips. Expired or improperly stored test strips can deliver incorrect results. Such misleading blood glucose readings can cause severe harm, including death [6].

Why Do the Test Strips Expire Quickly?

Glucose test strips depend on enzymes. These enzymes (glucose oxidase or glucose dehydrogenase) break down over time. When this happens, the test results become undependable.

Enzyme degradation happens more quickly if the strips are exposed to extreme temperatures or humidity. Under these circumstances, test strip results may become undependable even before the printed expiry date [3].

Glucose test strips are supplied in an airtight container and must be stored at the temperature recommended by the manufacturer for the best results. We should open the container, remove one strip, and close the container quickly. Exposure to moisture will damage these test strips [7].

Can I Use Expired Test Strips?

Manufacturers of glucose test strips must mention an expiration date on their products. The strips do not become worthless immediately after this date has passed. However, the possibility of inaccurate results is higher. Erroneous results become more likely as time elapses beyond the expiration date.

In an emergency, we can use a test strip that has recently passed its expiration date, keeping in mind the possibility of an inaccurate result. For safety, we should use strips only within their expiration dates. This is vital because a single faulty strip or reading can lead us to a treatment decision that can be harmful or even fatal [3].

Frequently Asked Questions (FAQs)

Are Test Strips of Different Models Interchangeable?

There are several brands of glucometers and test strips available commercially. Each has the same basic methodology but differs in design and technology. Each strip must be used only with the glucometer designed for use with it.

Mixing and matching are not recommended. Using a glucometer with strips made for another brand of machine is very likely to give inaccurate and dangerous results.

Do Lancets Expire?

Lancets are products regulated by the US Food and Drug Administration and are required to carry an expiration date. These devices are sterilized and packed to ensure our safety from infection. We should only use them within the recommended period, not after the expiration date.

Lancets do not give inaccurate results if used beyond their expiration dates. The danger is that they may no longer remain sterile. Using lancets beyond the expiration date exposes us to the hazard of infection. Diabetes makes us vulnerable to infections, and we should never take such risks.

Lancets and other finger-prick devices should never be shared. We should properly dispose of single-use lancets after using them once. Other fingerstick devices are meant for multiple uses but only for one person. Sharing lancets and similar devices exposes us to the risk of infections like human immunodeficiency virus (HIV), hepatitis B, and hepatitis C [8].

What is the Expiration Date of Sinocare Test Strips?

Sinocare test strips have an expiration date of two years after manufacture as long as the containers remain sealed. Once the container is opened for use, all the strips should be used within three months. Any remaining strips after three months should be discarded, as they may give unreliable results.

Final Thoughts

Blood glucose measurement is a vital part of diabetes management. It is crucial to regularly measure and record these numbers to guide treatment and control of this lifelong disorder.

Persistent high blood glucose levels in diabetes can cause disorders of the heart, kidneys, nerves, and other organs. Low blood glucose levels (hypoglycemia) can cause nervousness, shakiness, perspiration, dizziness, sleepiness, and confusion. If left untreated, hypoglycemia may lead to unconsciousness or seizures. Thus, measuring blood glucose levels as advised and regulating our treatment is essential.

Blood glucose strips are often expensive, and it is tempting to use expired strips. We should be aware that using glucose strips beyond the expiration date or more than three months after opening the container can give unreliable blood glucose readings. Such results can lead to unnecessary and dangerous changes to our treatment. In the interest of our safety, we should never use expired glucose test strips.

References

1. World Health Organization. Diabetes. {https://www.who.int/health-topics/diabetes#tab=tab_1}.
2. Centers for Disease Control and Prevention: Diabetes Basics. { https://www.cdc.gov/diabetes/basics/index.html}
3. Diabetes UK: Can people with diabetes use expired blood glucose test strips? https://www.diabetes.co.uk/blog/2015/05/can-people-with-diabetes-use-expired-blood-glucose-test-strips/
4. Gainey Wilson K., Ovington, P., & Dean, D. (2015). A Low-Cost Inkjet-Printed Glucose Test Strip System for Resource-Poor Settings. Journal of diabetes science and technology, 9(6), 1275–1281.{ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4667310}
5. American Diabetes Association: The Big Picture: Checking Your Blood Glucose. { https://diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/checking-your-blood-sugar}
6. US Food and Drug Administration: FDA warns about risks of using home use test strips that are pre-owned or not authorized for sale in US, including those for glucose, warfarin. { https://www.fda.gov/news-events/press-announcements/fda-warns-about-risks-using-home-use-test-strips-are-pre-owned-or-not-authorized-sale-us-including}.
7. Centers for Disease Control and Prevention: Monitoring Your Blood Sugar. { https://www.cdc.gov/diabetes/managing/managing-blood-sugar/bloodglucosemonitoring.html}.
8. Centers for Disease Control and Prevention: Infection Prevention during Blood Glucose Monitoring and Insulin Administration { https://www.cdc.gov/injectionsafety/blood-glucose-monitoring.html}.