'Modest' Benefit for Post-MI Flash Glucose Monitoring in T2D

Sara Freeman

October 21, 2020

Following a heart attack, there appears to be a "modest" benefit of using flash glucose monitoring over fingerstick testing to monitor blood glucose levels in patients with type 2 diabetes being treated with insulin or a sulfonylurea, according to investigators of the LIBERATES trial.

The results showed a nonsignificant increase in the time that subjects' blood glucose was spent in the target range of 3.9-10.00 mmol/L (70-180 mg/dL) 3 months after experiencing an acute coronary syndrome (ACS).
At best, flash monitoring using Abbott's Freestyle Libre system was associated with an increase in time spent in range (TIR) of 17-28 or 48 minutes per day over self-monitoring of blood glucose (SMBG), depending on the type of statistical analysis used. There was no difference in glycated hemoglobin A1c levels between the two groups, but there was a trend for less time spent in hypoglycemia in the flash monitoring arm.

Viewers Underwhelmed

"My overall impression is that the effects were less pronounced than anticipated," Kare Birkeland, MD, PhD, a specialist in internal medicine and endocrinology at Oslo University Hospital, Rikshospitalet, Norway, observed after the findings were presented at the virtual annual meeting of the European Association for the Study of Diabetes.

Others who had watched the live session seemed similarly underwhelmed by the findings, with one viewer questioning the value of devoting an hour-and-a-half session to the phase 2 trial.

However, the session chair Simon Heller, BA, MB, BChir, DM, professor of clinical diabetes at the University of Sheffield, and trial coinvestigator, defended the detailed look at the trial's findings, noting that it was worthwhile to present the data from the trial as it "really helps explain why we do phase 2 and phase 3 trials."

Strong Rationale for Monitoring Post-MI

There is a strong rationale for ensuring that blood glucose is well controlled in type 2 diabetes patients who have experienced a myocardial infarction, observed Robert Storey, BSc, BM, DM, professor of cardiology at the University of Sheffield. One way to do that potentially is through improved glucose monitoring.

"There's clearly a close link between diabetes and the risk of MI: Both high and low HbA1c are associated with adverse outcome, and high and low glucose levels following MI are also associated with adverse outcome," he observed, noting also that hypoglycemia was not given enough attention in post-ACS patients.

"The hypothesis of the LIBERATES study was that a modern glycemic monitoring strategy can optimize blood glucose levels in type 2 diabetes patients following MI with the potential to reduce mortality and morbidity and improve quality of life," Storey said. "The main research question of LIBERATES says, 'Do new approaches in glucose monitoring increase the time in range and reduce hypoglycemia?' "

Pragmatic Trial Design

LIBERATES was a prospective, multicenter, parallel group, randomized controlled trial, explained the study's statistician Deborah Stocken, PhD, professor of clinical trials research at the University of Leeds. There was "limited ability to blind the interventions," so it was an open-label design.

"The patient population in LIBERATES was kept as inclusive and as pragmatic as possible to ensure that the results at the end of the trial are generalizable," said Stocken. Patients with type 2 diabetes were recruited within 5 days of hospital admission for ACS, which could include both ST- and non-ST elevation MI. In all, 141 of a calculated 150 patients that would be needed were recruited and randomized to the flash monitoring (69) or SMBG (72) arm.

Stocken noted that early in the recruitment phase, the trials oversight committee recommended that Bayesian methodology should be used as the most robust analytical approach.

"Essentially, a Bayesian approach would avoid a hypothesis test, and instead would provide a probability of there being a treatment benefit for continuous monitoring. And if this probability was high enough, this would warrant further research in the phase 3 setting," Stocken said.

What Else Was Shown?

"We had a number of prespecified secondary endpoints, which to me are equally important," said Ramzi Ajjan, MD, MMed.Sci, PhD, associate professor and consultant in diabetes and endocrinology at Leeds University and Leeds Teaching Hospitals Trust.

Among these was the TIR at days 16-30, which showed a 90-minute increase per day in favor of flash monitoring over SMBG. This "seems to be driven by those who are on insulin," Ajjan said, adding that "you get almost a 3-hour increase in time in range in people who are on insulin at baseline, and you don't see that in people who are on sulfonylurea."

Conversely, sulfonylurea treatment seemed to drive the reduction in the time spent in hypoglycemia defined as 3.9 mmol/L (70 g/dL) at 3 months. For the whole group, there was a 1.3-hour reduction in hypoglycemia per day with flash monitoring versus SMBG, which increased to 2 hours for those on sulfonylureas.

There also was a "pattern of reduction" in time spent in hypoglycemia defined as less than 3.0 mmol/L (54 g/dL) both early on and becoming more pronounced with time.

"Flash glucose monitoring is associated with higher treatment satisfaction score, compared with SMBG," Ajjan said.

Although A1c dropped in both groups to a similar extent, he noted that the reduction seen in the flash monitoring group was associated with a decrease in hypoglycemia.

There was a huge amount of data collected during the trial and there are many more analyses that could be done, Ajjan said. The outcome of those may determine whether a phase 3 trial is likely, assuming sponsorship can be secured.

The LIBERATES Trial was funded by grants from the UK National Institute for Health Research and Abbott Diabetes Care. None of the investigators were additionally compensated for their work within the trial. Stocken had no disclosures in relation to this trial. Ajjan has received research funding and other financial support from Abbott, Bayer, Eli Lilly, Johnson & Johnson, and Novo Nordisk.

SOURCE: Ajjan R et al. EASD 2020. S11 – The LIBERATES Trial.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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