Decoding the FDA’s Perspective on Diabetes Devices
by jessica swienckowski
The diaTribe team has been attending more FDA meetings of late, and two in particular struck us as very valuable for patients. This Learning Curve will give you a window into recent FDA meetings concerning the accuracy of insulin infusion pumps and blood glucose meters. In addition, we discuss how accurate current blood glucose monitors are and give you tips on what you can do to obtain the best test results possible.
In general, both meetings we attended were focused on patient safety. Specifically, one addressed the accuracy of insulin infusion pumps and the other the accuracy of self-monitoring blood glucose (SMBG) devices. Although we felt the insulin infusion pump meeting was less productive than we had hoped, we were surprised to see an initiative very recently launched by the FDA setting a higher bar for the kind of information and risk assessment required of manufacturers producing pumps. At the meeting in March, we got the sense that manufacturers do a pretty good job keeping pumps safe. At the same time, insulin is obviously a treacherous medication (more accidents happen in hospitals with insulin than with any other drug, and that is in a space surrounded by doctors!), so additional safety measures are clear positives. While the FDA did not make specific recommendations at that meeting, an upcoming meeting open to the public in May is slated to discuss how manufacturers, health care providers, academics, the FDA, and patients can work together to further improve the safety of these insulin delivery devices. For more on the initiative to improve the safety of pumps and the upcoming meeting, click here. We will keep diaTribe readers posted on what happens at the next meeting and we are working to better understand what the FDA has recently recommended to companies under the new initiative.
While insulin pumps no doubt play a very important role in many of our reader’s lives, particularly those with type 1 who are intensively managed (though the number of type 2 pumpers is growing rapidly), there is no device more ubiquitous in the “diabetes medicine cabinet” than the blood glucose meter. The goal of the SMBG device meeting that took place in late March was to discuss whether or not current accuracy standards, based upon the recommendations of the International Organization for Standardization (ISO; a nongovernmental organization composed of members from various national standards organizations), are sufficient.
As we understand it, the FDA began to rethink the accuracy guidelines for meters in September of 2009, and is looking to tighten the accuracy requirements for meters in the US regardless of the international guidelines. We were pleased to see that the FDA meeting was characterized by a distinctly cooperative tone – the FDA, healthcare professionals, industry, and patients are all working together to arrive at the best recommendations for future accuracy requirements. No changes in guidelines have been made at this time, but it seems likely from the meeting that the FDA will recommend incrementally tighter standards in the near future. For the remainder of this learning curve, we will discuss what current accuracy requirements mean for your readings, what factors influence accuracy, and how patients can obtain the best test results.
how accurate are current meters?
The FDA currently uses the standards set by the ISO for accuracy of blood glucose meters. These guidelines require meters to be accurate within 20% of the real glucose value, 95% of the time, when glucose is over 75 mg/dl and accurate within 15 mg/dl, 95% of the time, when blood glucose is below 75 mg/dl.
Below are the ISO guidelines outlining the accuracy currently required by the FDA for at-home blood glucose monitors:
|Actual Blood Glucose Level||Allowable Error|
|75 mg/dl or greater||±20% of actual reading (95% of the time)|
|Below 75 mg/dl||±15 mg/dl of actual reading (95% of the time)|
Whether you feel current requirements are appropriate or not, there is no disagreement that most patients use blood glucose values to make critical decisions about insulin use and even to make choices about behavior (i.e., operating a vehicle). Under the current requirements, if your blood glucose is really 100 mg/dl, your meter could read anywhere between 80-120 mg/dl. This likely will not make a big difference in how you choose to manage your diet, activity, or medication use. On the other hand, as the blood glucose rises, the meter reading could be more inaccurate, so for a blood glucose level of 160 mg/dl, the meter could display a number in the range of 128-192 mg/dl. Depending on what number is obtained in this range of possible glucose values, you would likely take different treatment actions (i.e., dose insulin at the higher end of the range and do nothing at the lower end). For blood glucose values below 75 mg/dl, meters are required to be accurate within ±15 mg/dl 95% of the time. This means for a blood sugar of 60 mg/dl, your meter could display a number in the range of 45-75 mg/dl.
You should keep in mind that these accuracy requirements only pertain to the “out of the box” error, so to speak – this is the error allowed under conditions in which the tests strips, meter, and the sample are handled exactly according to recommendations and under the assumption that no other influences are affecting accuracy. In reality, error could be higher than the ±20% or ±15 mg/dl, depending on a number of factors.
what factors influence accuracy?
Several factors can influence the accuracy of blood glucose strips and meters:
Patient Physiology: Meters may not be as accurate in patients with anemia (an abnormal level of red blood cells usually related to other illnesses) or sepsis (wide-spread inflammation associated with severe illness).
Environmental Interferences: Meters may be less accurate in high-altitude conditions, including on airplanes. In some cases the chemistry used may require a normal oxygen supply to work properly, being inaccurate at both low and high oxygen levels. Additionally, even other medications a patient is taking can affect the accuracy of a meter, as well as extreme temperatures and humidity. Most of these interferences are related to limitations of the chemistry used in the strips.
User-Generated Error: Several different user errors can also contribute to reduced accuracy of blood glucose monitors. In the next section, we discuss steps you can take to ensure you obtain the best results possible.
what can patients do to obtain the best test results?
You can help improve the quality of your blood glucose readings by following a few extra steps:
Wash, Rinse, and Dry Your Hands: Almost every patient cheats on this one, but it is one of the simplest things you can do to improve the quality of your testing. If you eat an orange or cookie for a snack in the morning and then test your blood sugar before lunch without washing your hands, your reading might be sky high, but completely false – you never know what you’ve gotten on your hands over the course of a day, so it is best to start with a clean slate before testing.
Keep Your Supplies Up To Date: Keep track of when your test strips expire. It is easy to convince yourself that they could still be good, but when you are using the readings to make decisions about your insulin doses, you want to make sure you are using fully functional strips! Along the same lines, you should be careful to store your strips in a safe place where they won’t be damaged—the glove box of your vehicle isn’t the best idea if you live in a hot area.
Perform Quality Control Tests: You may never have performed a quality control test on your meter or strips, but it is still a good idea to utilize this safety precaution built into the device. You can usually buy control solution at your local pharmacy, although it typically costs around $15 and expires in 30 days. We recognize this cost is high (and this fact was clearly discussed as a barrier with the FDA), but even if you can only perform control tests every now and then, it is better than never.
Read the Patient Information: Each manufacturer provides an insert in the box and/or on the box that lists information pertaining to the limitations of their blood glucose strips (i.e. temperature range, interfering medications, hematocrit levels).
When in Doubt, Check Again: If your meter reading seems inconsistent with how you are feeling, take the time to check your blood sugar again before dosing insulin. Remember, the standards are required to be met 95% of the time. You may have an “outlier” result that is outside of the 20%.