Diabetes Test Strips

Diabetes test strips are an easy way to test your blood sugar, aka your glucose levels. This is important for people with diabetes. The strips work with glucose meters to “read” your blood sugar levels.

Knowing your blood sugar levels helps you manage your disease. When you regularly check your blood glucose, you’ll learn which foods, medications, and activities affect your blood sugar in a good or bad way.

How to Use a Test Strip

To check your blood sugar, you:

  • Put a test strip into your blood glucose meter.
  • Prick your fingertip with the meter’s tiny needle (called a lancet).
  • Squeeze out a drop of blood and touch it with the edge of the test strip.

Within seconds, the glucose meter will give you a blood sugar reading.

You can only use a test strip once. That means you’ll have to take out a new one every time you check your blood sugar. Your doctor will tell you how often to check. It may be as much as 10 times a day if you have type 1 diabetes. Or it may be just twice a day if you have type 2 diabetes.

How Test Strips Work

Diabetes test strips pack a lot of technology into a small space. The plastic strips are coated with a very thin layer of gold. The gold is cut into a pattern that becomes the strip’s circuit.

One end of the strip also has a coating of chemicals. They soak up your blood like a sponge and turn the glucose into electricity.

An electrical signal travels from the strip to the meter. The number you see on the meter is the speed of the electrical current. More blood sugar means a stronger signal. A stronger signal means a higher number on your blood glucose meter.

Purchasing Test Strips

You can get diabetes test strips in most places that sell medical supplies, like a pharmacy, or even online. If cost is a concern, talk to your doctor about ways to save money.

To help lower the cost of test strips, you can:

  • Look for coupons in magazines and drug store circulars.
  • Call or email the diabetes supply company for samples.
  • Buy generic brands.
  • Check out diabetes support websites, some of which offer diabetes supplies to people in need.

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Test Strip Accuracy

You may have heard that glucose meters aren’t always accurate.

Studies have shown that the accuracy of diabetes test strips can vary. Researchers tested the accuracy of 18 blood glucose monitoring systems in three studies. Here’s some of what they found:

  • Six of the systems met the standard for accuracy in all three studies.
  • Five met the standard in two studies.
  • Three met the standard in one study.
  • Four didn’t meet the standard for accuracy in any of the studies.

The good news is that the FDA now calls for all new blood glucose meter readings to be within at least 15% of the lab’s measurements. This means your reading must be accurate at least 19 times out of 20. And all new studies must have at least 350 people with diabetes, more than originally required.

Test Strip Tips

Test strip problems are common causes of inaccurate readings. To make sure your test strip sends the right information about your blood glucose:

  • Don’t use damaged strips.
  • Don’t use expired strips.
  • Store strips away from heat, moisture, and humidity.
  • Make sure they’re the right strips for your meter.
  • Depending on the test strip brand, a new test strip box may need to be calibrated or coded to work correctly.

Just because a test strip fits in your glucose meter doesn’t mean it will work. When you use the wrong strips:

  • Results could be inaccurate.
  • You could get no result.
  • The meter won’t turn on.

Test strip problems aren’t the only reasons your readings might be wrong. Others include:

  • A dirty meter
  • Unwashed hands
  • Temperature changes (cold, heat, humidity)
  • Not enough blood on the strip
  • Wet fingers

Check your meter with control solution every few weeks. And make sure the solution isn’t too old -- it’s only good for about 3 months after you open it.

WebMD Medical Reference Reviewed by Brunilda Nazario, MD on August 27, 2019

Sources

SOURCES:

American Diabetes Association: “Anatomy of a Test Strip.”

Diabetes Care: "Investigation of the Accuracy of 18 Marketed Blood Glucose Monitors.”

Diatribe.org: “FDA Publishes Final Recommendations on Blood Glucose Meter Accuracy.”

Joslin Diabetes Center: "Little Things that Can Have a Big Impact on your Blood Glucose Reading,” “Money Saving Strategies for Diabetes Care Supplies.”

Journal of Diabetes Science and Technology: "Lot-to-lot variability of test strips and accuracy assessment of systems for self-monitoring of blood glucose according to ISO 15197.”

Mayo Clinic: "Blood sugar testing: Why, when and how,” “Blood glucose monitors: What factors affect accuracy?"

MIT School of Engineering: "How do glucometers work?”

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