according to the authors of a noninferiority trial published in the April issue of Diabetes Care.
Before December 2016, continuous glucose monitoring (CGM) was approved by the Food and Drug Administration for use only as an adjunct to standard home blood glucose monitoring (BGM), which was required to confirm the continuous glucose monitoring reading before making a decision on insulin dosing.
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In this randomized, noninferiority trial, 217 participants with type 1 diabetes who used an insulin pump were randomized either to CGM only (142 individuals) or to CGM with additional BGM before an insulin bolus was administered (75 individuals).
The primary outcome of the 26-week trial was time in the range of 70-180 mg/dL, according to findings from the CGM, and the study found that mean time in this range was the same for the two groups: 65%.
There were no severe hypoglycemic events in the CGM-only group, and only one in the CGM plus BGM group. There were also no significant changes from baseline to 26 weeks in other metrics of glucose control for mean glucose, hyperglycemia, hypoglycemia, and glycemic variability, and no significant differences between the two groups. The results were also similar for subgroups of age, duration of disease, education, use of CGM before study enrollment, baseline hemoglobin A1c, and baseline time in range.
“In addition to randomization and multiple center participation, the strengths of this study include a high degree of participant retention, CGM use, and treatment group adherence,” the authors wrote. “Notably, there was good separation between the treatment groups in the number of BGM tests per day, particularly when recognizing that two of the BGM measurements per day were required for CGM calibration and that, according to the protocol, the calibrations were performed at times such that they would not influence insulin bolusing.”
The authors said the results were likely to be equally applicable to individuals who use multiple daily insulin injections rather than an insulin pump, as the accuracy of the CGM sensor was just as relevant to this group.
They stressed that one major limitation of the trial was that it only included adults with well-controlled type 1 diabetes who were likely to adhere to the study protocol, and it excluded those with less well controlled disease.
Given this, they called for future studies to examine the safety of CGM alone in young people and adults who might be less compliant with their diabetes control, such as those with higher HbA1c levels, who test their blood glucose fewer than four times a day, and who are hypoglycemia-unaware.
“The application of this trial’s results to clinical practice can benefit people with T1D by reducing their burden of multiple daily fingersticks when using CGM and can enhance the cost-effectiveness of CGM therapy by reducing the number of daily BGM test strips,” they wrote. “Furthermore, the demonstration that insulin dosing based on CGM alone is safe has applicability to assessing risk involved with artificial pancreas systems that automate insulin delivery based on CGM sensor glucose measurements.”
The study was funded by the Leona M. and Harry B. Helmsley Charitable Trust, and Dexcom provided the CGM systems used in the trial. Authors declared speakers fees, consultancies, board positions and other funding from a range of pharmaceutical companies, including Dexcom. One author declared stock in Dexcom.