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Innovative Glucose Sensing Device In Type 1 Diabetes Patients With Hypoglycemia

Safety and effectiveness of FreeStyle Libre glucose-monitoring system

Controlling blood glucose levels at an optimum range to prevent diabetes-related microvascular and macrovascular complication is of utmost importance. Thus, several devices have been manufactured to closely monitor the blood sugar to prevent hypoglycemic events. One such device, the FreeStyle Libre glucose-monitoring system by Abbott Diabetes Care, serves this purpose. It consists of a glucose sensor inserted into the back of the upper arm for a maximum of 14 days and readings are obtained by waving a scanner over the sensor. It helps to improve glycemic control by providing new real-world data that measures the interstitial fluid glucose levels in real time. Although, it is cheaper, offers longer sensor wear, and does not require calibration, it does not alert the patients about hypo- or hyperglycemic event.

In a prospective, open-labeled, multicenter, and randomized parallel study design, 328 adult patients with well-controlled T1D (HbA1c <7.5%) were enrolled from 23 European diabetes centers. The study included ≥ 18-year-old patients with T1D for ≥ 5 years, been on insulin for ≥ 3 months and reports self-tested blood glucose levels to a minimum of 3 times daily for at least 2 months prior to initiation of study. The study evaluated the impact of the FreeStyle system on T1D patients with a hypoglycemic event in comparison to self-monitored blood glucose testing. The primary outcome of the study was the change in time in hypoglycemia (<3.9 mmol/L [70 mg/dL]) between baseline and 6 months. The purpose of the study was to assess whether a factory-calibrated, sensor-based, flash glucose-monitoring system compared with self-monitored glucose testing reduced exposure to hypoglycaemia in patients with type 1 diabetes.

Outcomes were evaluated in 119 patients in the intervention group and 120 patients in the control group out of 120 and 121 participants respectively. Average time in hypoglycemia changed from 3.38 hr/day at baseline to 2.03 hr/day at 6 months in the intervention group and from 3.44 hr/day to 3.27 hr/day in the control group; with the between-group difference of −1·24 (P value < 0.0001), thus a 38% reduction in time in hypoglycemia in the intervention group. A total of 13 adverse events and 10 serious adverse events with five in each group were reported by nine participants, but none of them related to the device. Also, no safety issues related to the device were reported.

The primary and secondary endpoints were assessed in the full analysis set, including all randomized participants except those with a positive pregnancy test during the study. The primary endpoints were assessed by analysis of covariance comparing treatment groups with study center, insulin administration method, and baseline time in hypoglycemia as covariates. Changes in the reported outcome measures and quality of life were calculated by comparing scores from the control and intervention group by analyzing covariance on baseline values, study center, and insulin administration method. The study showed that this novel device had well-controlled T1D and reduced the time spent in hypoglycemia. However, future studies are needed to assess the effectiveness of this technology in patients with less well-controlled diabetes and in younger age groups.

The new data proves that more scans mean better control of hypoglycemic events. The data consisted of > 400 million individual glucose measurements from 50,831 FreeStyle Libre readers and their uploaded anonymous data. Overall, the patients performed an average of 16.3 scans per day. When divided into 20 equally sized groups by scan rate (2,542 in each), HbA1c dropped from 8% to 6.7% in the lowest to highest scan rate respectively. Also, hypoglycemia rates < 70, 55, and 45 mg/dL dropped by 15%, 40%, and 49% (all P < 0.001) and the time spent with glucose levels > 180 mg/dL decreased from 10.4 to 5.7 hours/day (P < 0.001), while time in the range of 70 – 180 mg/dL improved from 12.0 to 16.8 hours/day (P < 0.001). The data provides substantial evidence and reaffirms the powerful impact of FreeStyle Libre. With a swipe, it is changing how diabetes was managed for decades and it is empowering patients to take action and live healthier lives.

According to Dr. Mohammad Ajjan, people prefer this device due to its simplicity and the data produced. Another physician, Dr. Chong Ahn, mentioned that the insulin-requiring type 2 diabetes populations is likely the primary market for this device versus T1D because of the loss of passive alarm for hypoglycemic event, which is a significant disadvantage for T1D patients. Another downfall of this device is the cost and reimbursement issue. Although the price is significantly less than conventional continuous glucose monitoring, it is still a bit more than blood glucose monitoring. Currently, the FreeStyle Libre device is either partially or fully reimbursed in more than 12 countries in selected patients, but hopefully in the near future lowering the price will accommodate a broader group of patients.

Practice Pearls:

  • FreeStyle Libre glucose monitoring system use resulted in significant reduction in time and incidence of hypoglycemic event.
  • Sensor-based system to monitor glucose accommodates patients as an alternative to conventional self-monitoring of blood glucose.
  • Due to the convenience, the device can be used frequently and it allows a tight control of blood glucose monitoring in diabetes patients.



1. Bolinder J, Antuna R, Geelhoed-Duijvestijn P, Kroger J, Weitgasser R. Novel glucose-sensing technology and hypoglycaemia in type 1 diabetes: a multicentre, non-masked, randomized controlled trial. The Lancet. Sept 12, 2016; 388: 2254-2263. http://dx.doi.org/10.1016/S0140-6736(16)31535-5

2. DOI: http://dx.doi.org/10.1016/S0140-6736(16)31535-5

3.“FreeStyle Libre Flash Glucose Monitoring System.” FreeStyle Libre Flash Glucose Monitoring System.  Abbott Laboratories Limited, 2017. Web. Mar 2, 2017. < https://freestylediabetes.co.uk/our-products/freestyle-libre>

4.Tucker, M. E. “‘Real-world’ Benefit Shown for FreeStyle Libre Glucose Monitor.” Medscape. Medscape Medical News, 21 Feb. 2017. Web. 02 Mar. 2017.