We thank Seibold (1) for his interest in our randomized study comparing real-time CGM (rtCGM) and intermittently scanned CGM (isCGM) in patients with type 1 diabetes (T1D) and normal hypoglycemia awareness during physical activity and over the subsequent home phase (2).
We acknowledge the challenges associated with using outcomes from the isCGM (FreeStyle Libre) and rtCGM (Guardian Connect Mobile) devices in our study. Nevertheless, we disagree that this disqualifies any comparisons. It does, however, stimulate further discussion.
We agree that different sensors may have different performance characteristics, especially at low glucose range (3). However, there are more similarities in hyperglycemia (3). In fact, rtCGM was superior to isCGM not only in hypoglycemia but also in hyperglycemia (>10.0 mmol/L [>180 mg/dL] and >13.9 mmol/L [>250 mg/dL]) during postrandomization in the Comparison of CGM in Randomized Study of Real-time and Intermittently Scanned Systems in T1D With Normal Awareness of Hypoglycemia (CORRIDA) trial. Additionally, Seibold did not provide any supporting evidence for his statement that iPro2 and Guardian Connect Mobile used in the CORRIDA trial have significantly different performance. We used the same Enlite sensor with the same characteristics for Guardian Connect Mobile and iPro2. Reference no. 4 in his letter is irrelevant, as it describes the performance of different system that was not used in our study. In addition, similar design with two isCGM system (Libre and Libre Pro) was used in the Abbott-sponsored IMPACT trial (4).
As Seibold correctly stated, there were no significant differences including gender between the CORRIDA study arms at the baseline. Moreover, we used protocol for physical activity eliminating excess exercise load for female participants. We do not think that the number of patients included in our study represents a significant limitation, as we performed valid power analysis (2). In addition, the CORRIDA represents the largest published head-to-head randomized, controlled trial comparing rtCGM and isCGM to date.
We have already discussed the short duration of the study as a limitation in our article (2). Although our study was originally planned as a 6-month follow-up with crossover design, the isCGM sensors were available only on prescription and not on the open market at the time. Therefore, it was not easy to buy enough isCGM sensors for research purposes. However, all patients were provided isCGM/rtCGM sensors on prescription at the end of the trial and were willing to participate in the subsequent extension phase of the CORRIDA study. The results of the extension phase will be available soon. Additionally, we are now finalizing the CORRIDA LIFE clinical study (a large, nonrandomized prospective study). Both trials use A1C as the primary outcome. In this case, A1C represents an externally valid outcome of diabetes control. Therefore, the results of these independent studies may provide new insights whether the results of the current CORRIDA study provide clinically relevant comparisons.
Article Information
Funding. This study was initiated, designed, and performed by the investigators and supported by Agency for Healthcare Research (AZV) of the Czech Republic grant 15-26705A (program RVO-VFN00064165) and by the Research Project of Charles University (Progres Q25).
Duality of Interest. J.Š. has received speaker honoraria and consulted for Abbott, Dexcom, Inc., Eli Lilly and Company, Medtronic, Inc., Novo Nordisk, and Roche. M.P. has received speaker honoraria and has consulted for Abbott, AstraZeneca, Boehringer Ingelheim, Dexcom, Inc., Eli Lilly and Company, Novartis, Novo Nordisk, Medtronic, Inc., Sanofi, Takeda Pharmaceutical Company, and Roche. No other potential conflicts of interest relevant to this article were reported.
- © 2021 by the American Diabetes Association