How Often Should You Check Control Solutions for Blood Glucose Meters?
I'm out of control solutions for both my blood glucose meters. And I must admit, I haven't thought about control solutions (which I'll abbreviate as CSs) for at least a year, ever since I received my most recent meter, and dutifully ran the CS on it to verify that the device was working within specs. It was. And I quit doing CS testing then and there.
As most PWD should be aware, control solutions are liquids which are dispensed in small vials that contain a fake blood concoction with a known glucose level. The solution is applied to one of those very expensive test strips (just like a normal blood test would be done), and the meter's reading lets you know that your meter and strip are working well together. Or not. Mine always have been. And since I easily get bored spending time and money to show that the manufacturer can indeed produce strips that work with their meter, I ceased further CS testing.
A few days ago, I got a "Dear Customer" letter from the maker of one of my meters, informing me that if one is guilty of not "thoroughly shaking the bottle prior to use", that the apparent control test results may be higher, or not recognized as control tests by the meter. Needless to say, the letter awoke some vague memories from deep in the back of my brain of testing with CSs. I rummaged around in my collection of old meter boxes, and eventually found the box in which this particular brand of meter had originally been packaged. Sure enough, inside the box there was an undisturbed mini-vial of control solution — unsurprisingly, it was outdated.
I checked the website of the company where I had purchased the meter, looking to see what the cost of a vial of control solution might be: it was $12.99. Not too bad, all things considered. I placed an order.
I then Googled "how often to check control solutions for blood glucose meters" to see if there was any guidance on what I'd need to do to get back in control. And found a fascinating discussion at Control Solution = Better Control?. It seems that some researchers did a survey about CSs, and titled their report An evaluation of the barriers to patient use of glucometer control solutions: A survey of patients, pharmacists, and providers. They found that:
- 23% of 60 people with diabetes who were surveyed said they used CSs as part of their testing routine.
- Only 56% of doctors said they recommended using CSs to their patients.
- Only 14% of pharmacists said they recommended it to people who were buying other BG test supplies: the researchers found that out of 25 pharmacies that were surveyed, only one had control solution displayed in an area where patients could see it.
- All pharmacists surveyed said they were familiar with control solution, and 61% said they believed it should be a routine part of blood glucose management. Yet only 39% said they regularly stocked control solution, and 43% said they never actually recommended it to patients; 43% also said they sometimes recommended it.
- Out of the people with diabetes who were surveyed, 67% said they didn’t use control solution because they didn’t know about it.
- Of the 32 doctors who were surveyed (only one endocrinologist), 62% indicated that they were familiar with CS, and 44% never recommend it. Others said they didn’t think it was needed with newer meters.
This wasn't the first time such results were obtained. In another report, SMBG Out of Control The Need for Educating Patients About Control Solution, 18 patients or parents of T1DM kids were surveyed: 58% didn't used CSs.
The latest editorial on the subject, Control Solutions for Blood Glucose Meters: A Neglected Opportunity for Reliable Measurements?, the author concluded that "usage of CS can be an additional way to make a costly and cumbersome diagnostic procedure more reliable and should therefore gain more attention. Unfortunately, to my knowledge we have no data from clinical studies (or real-world observations) available that show that usage of CS really improves safety and efficacy of SMBG by patients with diabetes."
I have another thought: I'd use CS more often if it were always included with the vial of strips whenever I purchase strips. And if the vial included a few more strips, and if the price of the strips plus CS wasn't inflated. After all, the purpose of CS is to verify that the manufacturer has done its job correctly in producing the strips — why should the consumer be financially penalized for doing the quality control that the manufacturer wants done?