Using a Continuous Glucose Monitoring System
Here's what we found from the five day trial. Josh only had one overnight low that we would have missed - in the high 60s. Night time lows were one thing CGMS seemed to find the most when people starting wearing them. Josh's low came, not surprisingly, on day when he had lots of exercise.
The most profound thing we learned was food related. Seeing a graphical depiction of blood sugar after a high fat meal was shocking. We could see the blood sugar start to spike hours after we expected. For the two high fat pizza meals we tried two different ways to manage it. For the first meal we did a normal meal bolus (he dipped low and then spiked high five to six hours later). For the second, we did a combination (or Dual wave) in which some insulin was delivered immediately and some was slowly given over the next four hours. The latter solution gave better blood sugar control with no evidence of any low or extreme spiking , but it still wasn't a great match.
We ultimately found, in consultation with our diabetes team and the technology team ,we needed to extend the bolus for a high fat meal such as pizza for as long as six hours! I never would have believed this without seeing the CGMS data. We also increased all his insulin to carbohydrate ratios and actually lowered basal rates around dinner time.
We could see that bolusing after eating at lunchtime did not match food and insulin well. Josh was doing this in the Fall as we worked out the challenges of the middle school cafeteria. I'll write a future blog on the efficacy of pre-dosing for food. It makes a big difference!
I like the potential of CGMS as a tool for improving blood sugar control. The JDRF study published in the New England Journal of Medicine showed a definite improvement in A1C of adults who used a CGMS, but the data did not appear to support such an improvement in teens and children. However a closer reading of that study shows that it was compliance with wearing the device that may have impeded the improvement in youth, particularly in teens. When they did wear the device they had better blood sugar numbers.
Wearing it continuously (meaning two sites) does not work for Josh at this point, but he's open to trying it in the future if we need it.
Maybe diabetes programs should develop protocols for a short term problem solving usage of the CGMS for teens and children. I wonder if the CGMS could become a part of a pump start to help set basal rates more effectively. I'd love to see a lending program of CGMS for families to use on an as needed basis to address immediate challenges like setting basal rates, dealing with growth spurts, reworking insulin to carb ratios and learning how to use extended/combination/square wave boluses to best meet the child's body's needs.
A quick note on insurance coverage - it was initially denied by our provider, but the denial was due to the hospital not sending in the "medical necessity statement". When the hospital sent it in and re-billed, the five day trial was paid.
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