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Reporting a Medication Error

Understanding the results on your blood glucose monitor screen

edb573a17581af3290eff07627fcedd0 MMore than 30 million—nearly 1 in every 10—Americans have diabetes. To help manage their condition, many people with diabetes use a small, portable glucose meter to measure the amount of sugar (glucose) in their blood. After pricking the skin with a sharp lancet (small needle), one places a drop of blood on a test strip inserted in the glucose meter. The glucose meter then displays the blood sugar level on the screen. People with low or high blood sugar readings need to make quick treatment decisions. If the blood sugar reading is low, the person needs to eat or drink a sugary food or beverage, like candy, glucose tablets, or orange juice. This helps raise the amount of sugar in the blood to normal limits. If the reading is high, the person may need to take more insulin. The extra insulin helps lower the amount of sugar in the blood. If the blood sugar reading is normal, no additional food or medicine is needed. Unfortunately, mistakes have been made when making these treatment decisions due to the way the blood sugar results are displayed on some glucose meter screens.

For example, the blood sugar reading on the screen of an ACCU-CHEK Inform II glucose meter has been repeatedly misinterpreted when it was displayed as an unfamiliar abbreviation.1 People were expecting a numerical blood sugar value to appear on the results screen (Figure 1). But instead, the abbreviation “RR LO” (Figure 2) or “CR LO” appeared on the results screen. “RR LO” is an abbreviation for “reportable range, low limit,” which means the blood sugar is below normal. “CR LO” is an abbreviation for “critical range, low limit,” which means the blood sugar is critically below normal. When these abbreviations appear, the correct treatment action is to eat or drink a sugary food or beverage to raise the amount of sugar in the blood because it is too low. Figure 1 4 glucose monitor

Two recent mistakes happened when “RR LO” appeared on the results screen, and the abbreviation was mistakenly thought to mean the blood sugar was high, not low.1 Below the abbreviation is an alarm code, “W-510” (Figure 2). Because the alarm code includes a number, the number “510” was mistaken as a very high blood sugar value. Both people took more insulin instead of eating or drinking a sugary food or beverage. The insulin lowered the blood sugar further to dangerously low levels. Sadly, one person died because of the mistake. 

Mistakes are also possible when the abbreviations “RR HI” and “CR HI” appear on the glucose meter screen.1 “RR HI” is an abbreviation for “reportable range, high limit,” which means the blood sugar is above normal. “CR HI” is abbreviation for “critical range, high limit,” which means the blood sugar is critically above normal.

Furthermore, it is not just consumers who can be confused by how information is displayed on the glucose meter’s results screen. When healthcare providers at two different Veterans Affairs medical centers viewed these codes during equipment testing, 1 in 10 misunderstood the abbreviation “RR LO.” As a result, they did not choose the correct treatment decision, which was to give the pretend patient a sugary food or beverage to raise the low blood sugar. In fact, almost half of the healthcare providers who misinterpreted the “RR LO” abbreviation gave the pretend patient additional insulin. None of the healthcare providers made a mistake when the glucose meter displayed the numerical blood sugar value--for example, 32 mg/dL--instead of an abbreviation. 

Here’s what you can do: If you use a glucose meter to test your blood sugar, learn how to use it so you fully understand all the possible blood sugar results that may appear on the screen. Read the instruction manual, paying particular attention to the meaning of any abbreviations or codes on the results screen. Companies that make glucose meters often have written instructions, quick reference guides, online tools, frequently asked questions, and customer care centers that can be contacted 24/7 for questions. Your local pharmacist can also help you understand how to use the glucose meter and interpret the results. If you switch to a different glucose meter, get training to use the new meter, as it may present the blood sugar results differently than your previous glucose meter. 

Figure 2 4 glucose monitor

Also, some glucose meters, including the ACCU-CHECK Inform II, can be set up to display only the numerical blood sugar results, without using confusing abbreviations. Ask the company’s customer care center if this is an option and how to set up your meter this way.

If you are unsure of the results on the glucose meter screen, call your pharmacist or the company customer care center for help. But first eat or drink a sugary food or beverage before you call if you believe the results mean your blood sugar is low, especially if you have any of the following symptoms of low blood sugar (hypoglycemia):

  • Hunger
  • Feeling shaky
  • Fast heartbeat
  • Lightheadedness
  • Dizziness
  • Confusion
  • Sweating
  • Headache
  • Irritability

Low blood sugar can affect your ability to think and react quickly, so it is important to eat or drink a sugary food or beverage before making the call. Always talk to your doctor if low or high blood sugars are a problem for you.


         1) Estock JL, Pham IT, Curinga HK, et al. Reducing treatment errors through point-of-care glucometer configuration. Jt Comm J Qual Patient Saf. 2018;000:1-12. [Epub ahead of print]. Available at: www.ismp.org/ext/85

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