A T1DCRN funded clinical trial published in Diabetes Care has shown that a pump with the ability to suspend insulin delivery when blood glucose levels begin to fall can reduce hypoglycaemic episodes without deterioration in glycaemic control.
The integration of real-time continuous glucose monitoring systems and pump therapy has been an important milestone in the management of type 1 diabetes, and advances in the technology field offers the potential to further improve clinical outcomes.
Hypoglycaemia is a feared short term complication of living with type 1 diabetes, and must be treated immediately to avoid loss of consciousness. Avoidance of hypoglycaemia is top of mind for people with type 1 diabetes, and many prefer to stay in a state of hyperglycaemia because of this, increasing the risk of long-term complications.
The Predictive Low Glucose Management System (PLGM) is the only commercially available sensor-integrated insulin delivery system in Australia that has been shown to reduce hypoglycaemia in in-clinic conditions and short outpatient studies. The pump, when used in conjunction with the Medtronic Enlite Sensor and Guardian 2 Link transmitter, has the “Suspend before low” feature, which suspends insulin infusion when hypoglycaemia is predicted.
The effectiveness and safety of this system has not previously been tested in a randomised controlled at-home setting over longer periods of time. This study therefore tested the effectiveness of PLGM in real life situations over 6 months in 154 young people aged 8-18 (mean 13.2yo), in an intent-to-treat analysis. The primary objective of the study was to compare average percentage of time spent in hypoglycaemia with PLGM versus Sensor-Augmented Pump Therapy (SAPT) alone. Hypoglycaemia was defined as sensor glucose (SG) <3.5mmol/L.
At baseline, the time with SG <3.5 mmol/L was 3.0% and 2.8% in the SAPT and PLGM groups, respectively. During the study, there was a reduction in time spent in hypoglycaemia that was greater with PLGM, and was persistent across the entire 6 month period (% time SG <3.5 mmol/L: SAPT vs. PLGM, 2.6 vs. 1.4, P < 0.0001).
A similar effect was also noted in time with SG <3 mmol/L (P< 0.0001). This reduction was seen both during day and night (P < 0.0001) for PLGM users, while patients in the SAPT group did not reduce time spent in hypoglycaemia during the day significantly but showed a mild reduction at night. Hypoglycaemic events (SG <3.5 mmol/L for >20 min) also declined with PLGM (SAPT vs. PLGM: events/patient-years 227 vs. 139, P < 0.001). There was no difference in HbA1c at 6 months (SAPT 7.6 ± 1.0% vs. PLGM 7.8 ± 0.8%, P = 0.35). No change in quality of life measures was reported by participants or parents in either group, and there were no PLGM-related serious adverse events.
This study was funded through the first phase of the Clinical Research Network (CRN), initially funded by the Department of Health and Ageing (DoHA), and now funded through a Special Research Initiative of the Australian Research Council. The study was led by Professor Tim Jones, who is also leading the current young person’s arm of the hybrid closed loop study. Through this study he also mentored previous Mentored Clinician Researcher Fellowship (MCRF) recipient Dr Mary Abraham.
The second phase of the CRN is taking technology even further: trialling a hybrid closed loop system in both young people and adults with type 1 diabetes. The hybrid closed loop system uses a similar pump, but with a more complex algorithm to automate basal insulin through the day and night when linked to a continuous glucose monitor.