Real-Time Continuous Glucose Monitoring (rtCGM) Improves Glucose Control In Type 1 Diabetes
Researchers from Charles University in Prague have found that real-time continuous glucose monitoring (rtCGM) is effective among those with type 1 Diabetes irrespective of what modalities are used to deliver insulin to the body.
The three year trial called COMISAIR (Comparison of Different Treatment Modalities for Type 1 Diabetes Including Sensor-Augmented Insulin Regimens) compared usage of insulin pumps, multiple daily injections (MDI), blood glucose testing and continuous glucose monitoring (CGM).
The longest duration of any CGM trial, real-time (not flash) CGM was superior to self-monitored blood glucose (SMBG), or fingerstick, testing at least four times daily in reducing HbA1c in patients using both pumps and MDI, with little difference between the two insulin delivery modalities.
A total of 94 patients with type 1 diabetes participated in this trial and each had to be using one of four treatment regimens:
1) insulin pump and rtCGM – 26 participants
2) insulin pumpand blood glucose testing – 25 participants
3) MDI and rtCGM – 22 participants
4) MDI and blood glucose testing – 21 participants
The participants were allowed to choose the insulin and monitoring option that met their individual needs, which the researchers said reflects real-life decision-making in most practices.
After three years, HbA1c levels were noticeably lower in the rtCGM groups; 52 mmol/mmol (6.9%) for rtCGM and insulin pump and 53 mmol/mol (7.0%) for rtCGM and MDI. This compared to HbA1c levels of 61 mmol/mol (7.7%) for users of insulin pump and blood glucose testing, and 64 mmol/mol (8.0%) for users of insulin pump and blood glucose testing.
A key measure of type 1 diabetes control is time in range, which is the proportion of time that blood glucose levels stay within a target range. The results showed that it was only the users of rtCGM that experienced significant improvement in this. Furthermore, time in hypoglycemia decreased only for the users of rtCGM and not for the groups using blood glucose testing.
Lead author Dr. Jan Šoupal commented in an interview with Thailand Medical News, "It is not so important how insulin is delivered, but more important is how patients with type 1 diabetes monitor their glucose. Individualization of treatment is important. However, according to the results of our trial, in the vast majority of cases, CGM is what makes the difference."
He further commented "CGM and multiple daily injections [of insulin] can be a suitable alternative to treatment with pumps and CGM for some patients," such as those who have achieved good control using that regimen, those who are only willing to accept one device on their bodies, or for reasons of accessibility/affordability.
Patients likely to do better with pump plus CGM regimens include those with the dawn phenomenon (a rise in blood glucose in the early morning) and those who are physically active and can benefit from temporarily lowered basal infusion rates. Patients with hypoglycemic unawareness may be ideal candidates for sensor-augmented pump therapy.”
Participants in the current study used either the Dexcom G4
or Medtronic Enlite
sensors, not the Abbott Libre
(ie, "flash" glucose monitoring or FGM). Where patients use FGM, many don't achieve HbA1c targets with either pump or injection therapy. That's probably due in part to the alarm feature of rtCGM but not flash monitoring and that flash monitoring is less accurate in the lower ranges of blood glucose levels. Real-time alarms are better than just having the data. It was also cautioned that in some cases the introduction of CGM or flash glucose monitoring might actually lead to an increase in HbA1c if the main initial effect is reducing hypoglycemic events, which should be explained to patients.
Reference: Glycemic Outcomes in Adults With T1D Are Impacted More by Continuous Glucose Monitoring Than by Insulin Delivery Method: 3 Years of Follow-Up From the COMISAIR Study ,Jan Šoupal, Lenka Petruželková, George Grunberger, Aneta Hásková, Milan Flekač, Martin Matoulek, Ondřej Mikeš, Tomáš Pelcl, Jan Škrha, Eva Horová, Jan Škrha, Christopher G. Parkin, Štěpán Svačina, Martin Prázný
Diabetes Care 2019 Sep; dc190888.https://doi.org/10.2337/dc19-0888