After three weeks using a CGM (continuous glucose monitor), I’m officially a convert. It is not without its limitations, which I outlined in my previous couple of entries. But this technology manages to give a level of detail and understanding into how blood sugar is behaving that is light years beyond what we can achieve with finger sticks alone. And that translates into better control, smarter choices, and a healthier life!
Today, I want to wrap up sharing my experience adjusting to the CGM, and talk about the future of this technology. So let’s start with where the CGM is going in the next five years. It is, of course, vitally important to the continuing development of the artificial pancreas. Medtronic, as many of you know, has introduced the world’s first hybrid closed loop system (approved by the FDA and scheduled to roll out in early 2017). This system still requires user input for bolus doses when consuming food (and input of estimated carbohydrates, though it will “correct for errors” if it see blood sugar rising too quickly and thinks the input number was too low, or lessen insulin if it sees a trend in the other direction), but it is designed to regulate background insulin fully automatically to keep the user to a target blood glucose reading of 120.
It will do this, of course, by communicating constantly with an integrated CGM. The fact that the FDA has given its seal of approval shows how far CGM accuracy has come in the last five years, and it continues to improve. In a recent interview, Kevin Sayer, the President and CEO of Dexcom, said he was hopeful that the FDA would soon approve the CGM for dosing (currently, the FDA does not officially approve the use of a CGM reading to make treatment decisions — hence the statement on CGM devices that they are meant to be used to see “trends only”). This will be a huge step forward, as it would allow insurance to treat the CGM as an equal device to finger stick meters, rather than treating it as a secondary device (and therefore one much less likely to be covered).
The biggest hurdle for accuracy is that the CGM, as mentioned in my previous posts, does not actually measure glucose in the blood, but rather in the interstitial fluid (fluid between the cells) under the skin. There is a lag between the interstitial glucose and blood glucose levels. This is why the accuracy of many CGMs diminish when numbers are moving quickly. However, the accuracy of the current generation of CGMs has been shown to be within 9% of laboratory tests, and this has historically been the benchmark for using a device for medical decisions, hence the optimism expressed by Kevin Sayer that soon the CGM will be approved for stand-alone use without needing the confirmation of finger stick tests for making treatment decisions. (And in fact, over the summer, an FDA advisory panel recommended allowing the use of the Dexcom G5 for making treatment decisions.)
As accuracy continues to improve and development on closed-loop systems moves forward, it seems clear that the CGM as a vital component of diabetes care will only increase. While nobody can predict the future with certainty, it seems very likely that within 5 to 10 years this technology will replace finger stick testing altogether, relegating our old meters to emergency back-up devices.
So now that we’ve discussed the technological side of things, let me wrap up with a summary of what the experience has been like living day-to-day with the CGM. First of all, while the device is marvelously useful and I can’t imagine going without it after living with it for only three weeks, it CAN drive you a little crazy. Why? Because you have constant, 24-hour access to your number! That’s a good thing, but at a certain point you’ve got to learn to hold back and let the CGM work in the background. The first few weeks, I found myself checking my number every five minutes! Yes, the information was useful, but the stress was not. Most people who switch to a CGM report a similar experience — that is, at a certain point you need to relax and let it do what it does without constantly watching the numbers like a hawk!
The other lesson I’ve taken from the first few weeks is similar. That is, don’t expect your numbers to be completely normal! Even the best controlled among us experience occasional highs and lows. Diabetes is not a disease that can be completely and totally normalized. It can be managed, and managed well, but at the end of the day, we still have a disease. And that disease WILL have an impact, no matter how well we manage it. What’s important is seeing the bigger picture. And the CGM is very useful for this. But it can also draw us into the minute-to-minute data that leads down a very obsessive and stressful path. My advice to anyone trying this technology is to keep your eye on the big picture. Use the information you’re receiving to understand the trends and make adjustments, but don’t go crazy every time your blood sugar moves over 140. Don’t expect perfection!
I hope these entries have been helpful for anyone considering a CGM. When all is said and done, I can’t recommend it enough. If you are able to add this to your treatment, I whole-heartedly endorse it. It’s not perfect, but it’s one phenomenally useful tool to help us in managing our condition!
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