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Insulin pump not essential for benefit from continuous glucose monitoring

October 25, 2019

By Marilynn Larkin

NEW YORK (Reuters Health) - In suboptimally controlled patients with type 1 diabetes, real-time continuous glucose monitoring (rtCGM) was superior to self-monitoring of blood glucose (SMBG) in reducing A1C and hypoglycemia, regardless of the insulin delivery method, a real-world nonrandomized trial reveals.

The study, online in Diabetes Care, is a repeat analysis of three-year results from the COMISAIR-2 trial, updated with an additional 29 patients.

COMISAIR (Comparison of Sensor Augmented Insulin Regimens) assessed the clinical impact of four treatment strategies in adults with type 1 diabetes (T1D): rtCGM with multiple daily insulin injections (rtCGM plus MDI) or with continuous subcutaneous insulin infusion (rtCGM plus CSII), or SMBG with either MDI or CSII.

"Before the initiation of this trial, most physicians believed that optimal diabetes management could only be achieved when rtCGM was used in combination with insulin pumps," Dr. Jan Soupal of Charles University in Prague told Reuters Health by email.

"In addition, in countries with existing reimbursement for rtCGM, the absence of studies in patients on multiple daily injections resulted in the willingness of payers to cover rtCGM only when combined with pumps," he explained.

"However, patients with poor metabolic control most often initiated treatment with an insulin pump without CGM. Therefore, clinical practice was missing a direct comparison of four basic treatment strategies in use for patients with T1D," he continued. "We had no idea which treatment is usually the most effective, and whether the improvement observed in patients treated by an insulin pump with rtCGM is attributable to the pump, the rtCGM, or both."

The expanded follow-up of COMISAIR-2 included 94 participants. The mean age was about 32; about half were men, and each treatment group included about 24 people. The main end points were changes in A1C; time in range (70-180 mg/dL); time below range (

At three years, the rtCGM plus MDI and rtCGM plus CSII groups had significantly lower A1C (7.0% and 6.9%, respectively), compared with the SMBG plus CSII and SMBG plus MDI groups (7.7% and 8.0%), with no significant difference between the rtCGM groups.

Significant improvements in percentage of time in range were seen in the rtCGM groups (with MDI, 48.7%-69.0%, and with CSII, 50.9-72.3%) and also in the SMBG plus CSII group (50.6-57.8%).

However, significant reductions in time below range were found only with rtCGM plus MDI (9.4%-5.5%) and rtCGM plus CSII (9%-5.3%).

Five severe hypoglycemia episodes occurred in the SMBG groups and two in the sensor-augmented insulin regimens groups.

"There are two important messages," Dr. Braun said. "First, the method of insulin delivery is not so important. CGM is what makes the difference. Second, this work might change current management of patients with T1D, when the frequent approach in those with suboptimal diabetes control is to initiate insulin pump treatment."

"The fact that these improvements were achieved in a real-world clinical study with only small drop-out in the rtCGM group demonstrates that use of this technology is both feasible in clinical practice and desirable among individuals with type 1 diabetes," he stressed.

Further, he noted, "finding that rtCGM with MDI is equivalent to sensor-augmented treatment in achieving glycemic goals (gives) patients the option to select the treatment modality that best meets their individual preferences and financial circumstances."

In addition, "There is an important impact for patients in my country," he said. "The results of the COMISAIR study have significantly contributed to the introduction of reimbursement for CGM in the Czech Republic, (enabling accessibility) to a wide group of patients with T1D."

Dr. Jacqueline Lonier of the Naomi Berrie Diabetes Center at Columbia University Medical Center in New York City commented in an email to Reuters Health, "The findings are consistent with what we observe anecdotally in clinical practice - real-time CGM allows patients with type 1 diabetes to monitor blood glucose levels more easily and more frequently, observe glucose trends, avoid hypoglycemia, and dose insulin more effectively in order to achieve blood glucose and A1c targets."

"As noted in the paper, knowledge of diabetes self-care and motivation to achieve and maintain blood glucose targets remain of utmost importance," she said. "CGM data is most useful when the patient knows how to interpret the information and implement insulin dose adjustments appropriately."

"Cost is an issue for many patients," she noted. "Although the devices are typically covered by insurance, patients' access is sometimes limited by high copays and deductibles, depending on the details of individual insurance plans."

"Compared to the models used in this study, the newest real-time CGMs are more accurate, can be worn for longer duration, and do not require fingerstick calibration," she said. "Hybrid closed-loop insulin delivery systems further integrate insulin pump and CGM devices, allowing for automatic adjustment of basal insulin rates."


Diabetes Care 2019.

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