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Real-World Evidence in Support of Continuous Glucose Monitoring

Oct 24, 2020
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: George McConnell, PharmD. Candidate, LECOM School of Pharmacy 

Insulin delivery method or blood glucose monitoring – which is more important?  The COMISAIR study assesses the impact of rtCGM.

Insulin is the mainstay for the treatment of type 1 diabetes. Many studies have found real-time continuous blood glucose monitoring (rtCGM) to be the preferred blood glucose monitoring system. It has been shown to lower HbA1c more and result in fewer hypoglycemic events than self-monitored blood glucose (SMBG). Despite the preponderance of the evidence being in favor of rtCGM, this study argues that randomized controlled trials do not translate well to real-world conditions. The authors say that randomized controlled trials, while good, do not show how patients will act outside of a study. The authors agree with previous studies that support rtCGM but feel that the information provided by those studies is incomplete. As such, this study sought to provide information when patients used rtCGM in the real-world.   

This study is a 3-year follow-up of the Comparison of Sensor-Augmented Insulin Regimens (COMISAIR) study. Patients in the study had to be >18, have had type 1 diabetes for >2 years, have an HbA1c of 7-10%, and be willing to participate in a 4-day training program, among others. Exclusion criteria included ketoacidosis or use of rtCGM within three months, and non-adherence to current therapy, among others. Patients selected from 4 different treatment regimens based on their preference and need, rtCGM with multiple daily injections (MDI) or continuous subcutaneous insulin infusions (CSII), or SMBG with MDI or CSII. No patients were discouraged from using any of the regimens, and investigator influence on the decision was minimal. Once each patient selected their regimen, they were given training and then started their treatment. Patients that chose SMBG were encouraged to do so at least four times per day. Patients were scheduled for 15 visits, one at baseline, week 2, month 3, and then every three months until their final visit at month 36. At each visit, every patient was screened for adverse events, and blood glucose data was obtained. All participants, regardless of therapy choice, were given a glucometer, either for care or for calibration of the real-time continuous blood glucose monitor. The primary endpoint of the study was the difference in HbA1c between the groups at three years. Secondary endpoints included change in glycemic variability, percentage of time spent in hypoglycemia, hypoglycemia incidence, and real-time continuous glucose monitoring usage in the groups using sensor-augmented insulin regimens.   

At three years, both groups that used rtCGM had lower HbA1c levels – an HbA1c of 7% for the MDI group (P = 0.0002) and 6.9% for the CSII (P < 0.0001) group when compared to the groups that self-monitored – 8% for the group using MDI (P = 1.000) and 7.7% for the group using CSII (P = 0.3574). There were no significant differences between both groups that used rtCGM or between both groups that SMBG. 48% of patients using sensor-assisted insulin regimens achieved an HbA1c of <7% at three years, compared to 9% of the self-monitored patients. While all patients saw an improvement in the amount of time spent in range (70-180 mg/dL), there was a significantly more significant amount of time spent in range by the groups utilizing rtCGM compared to those that self-monitored. When the subgroups were compared to each other, the P-value ranged from P < 0.0001 to P = 0.0016, though no significant difference was seen between the two groups using real-time glucose monitoring. Time spent in hypoglycemia (<70 mg/dL) was significantly reduced only in the groups using rtCGM: real-time monitoring plus CSII had a P-value of P = 0.0235; real-time monitoring plus MDI had a P-value of P = 0.0387. Severe hypoglycemia events (those where assistance was required) were seen five times in the self-monitoring groups: twice in those using CSII and three times in the group using MDI. The rtCGM groups had two episodes of severe hypoglycemia: once in the CSII group (when the patient was not wearing the monitor) and once in the group receiving MDI. A total of 3 episodes of ketoacidosis occurred, 1 in each of the self-monitoring groups and 1 in the real-time monitoring with the CSII group.   

The significant differences between the groups that used rtCGM and those that SMBG, versus no significant differences within the subgroups, led the authors to believe that rtCGM is more critical than how insulin is delivered. The authors believe that this  real-world study design furthers support for the use of rtCGM. There was no mention of patient satisfaction, though the high (>70%) willingness to use sensors and relatively low patient drop out (only three patients discontinued the study) along with the positive results indicate that patients are willing and able to make use of this technology.  

Practice Pearls: 

  • Real-time continuous blood glucose monitoring has, once again, been shown to result in better patient outcomes than self-monitoring blood glucose.  
  • Continuous blood glucose monitoring has a more significant impact on patient outcomes than insulin delivery does.   
  • This study’s real-world design indicates that patients are willing and able to use rtCGM outside of trials.   


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.” Diabetes Care,  


 George McConnell, PharmD. Candidate, LECOM School of Pharmacy