CGM improves HbA1c levels in T1D

Roshini Claire Anthony
28 Nov 2022
CGM improves HbA1c levels in T1D

Continuous glucose monitoring (CGM) with alarms for high or low blood sugar levels better controlled HbA1c levels than personal fingerstick monitoring in patients with type 1 diabetes (T1D), results of the FLASH-UK trial showed.

“Ability to monitor glucose without painful fingersticks is life-changing for many people living with T1D. With the use of second generation intermittently scanned CGM, we found significant improvements in average glucose levels and a reduction in both high and low glucose levels, helping people to spend more time with normal glucose levels,” said study author Dr Lalantha Leelarathna from the University of Manchester NHS Foundation Trust, Manchester, UK. [, accessed 21 November 2022]

The 156 participants aged 16 years (mean age 44 years, 44 percent female, 97 percent White) in this multicentre, open-label trial had T1D (for 1 year) with elevated HbA1c levels (7.5–11 percent; mean 8.6 percent) while on insulin therapy. All patients underwent blinded CGM for 10–14 days pre-randomization. They were then randomized 1:1 to undergo intermittently scanned CGM with optional alarms (intervention) or usual care of own monitoring of blood glucose levels with fingerstick testing (control).

The patients had T1D for a mean 21 years. Baseline HbA1c levels were 8.7 and 8.5 percent in the intervention and control groups, respectively.

At 24 weeks, HbA1c levels were significantly reduced in the intervention compared with the control group (mean 7.9 percent vs 8.3 percent; adjusted mean between-group difference, −0.5 percentage points, 95 percent confidence interval [CI], −0.7 to −0.3; p<0.001). [N Eng J Med 2022;doi:10.1056/NEJMoa2205650]

The patients in the intervention group were in the blood glucose target range (70–180 mg/dL) for a longer time than those in the control group (130 minutes longer per day or 9.0 percentage points higher than the control group). They were also in a hypoglycaemic or hyperglycaemic state (blood glucose level <70 mg/dL and >180 mg/dL, respectively) for a shorter period of time than those in the control group (time in hypoglycaemic state: 43 minutes shorter per day or 3.0 percentage points lower vs control; time in hyperglycaemic state: 86 minutes shorter per day or 6.0 percentage points lower vs control).

More patients in the intervention than control group had HbA1c levels 7.5 percent (adjusted odds ratio [adjOR], 2.47, 95 percent CI, 1.08–5.68) and decreases in HbA1c levels of 0.5 percentage points (adjOR, 4.74, 95 percent CI, 2.10–10.71).

In the intervention group, the number of participant-monitored blood glucose tests reduced over time from a mean 4.2 tests/day at baseline to 0.6 tests/day at week 24 (adjusted mean between-group difference, −3.3 tests/day). Difference in total daily insulin dose between the intervention and control groups at 24 weeks was small (adjusted mean between-group difference, −0.5 units).

Patient-reported outcomes, measured through Diabetes Treatment Satisfaction Questionnaire and Glucose Monitoring Satisfaction Survey total scores at 24 weeks, were improved in the intervention compared with the control group (adjusted differences, 7.0 and 0.7 points, respectively). However, measures of diabetes-related distress, depression, fear of injection and testing, and eating behaviours did not differ between groups.

Severe hypoglycaemia and ketosis (that did not warrant hospitalization) were recorded in two patients each in the control group, while one patient in the intervention group was hospitalized for diabetic ketoacidosis.

“CGM has been a critical tool for people living with diabetes, both to avoid painful fingersticks and to help manage glucose levels,” said Leelarathna. “This data adds to the growing body of evidence that demonstrates the technology [that] helps bring HbA1c levels closer to the target range, which ultimately decreases risks of further complications.” [, accessed 21 November 2022]

The authors acknowledged that the lack of data on alarm use precludes conclusions being made on whether the benefits of CGM could be attributed to the sensor or alarms. Additionally, patients with recurrent severe hypoglycaemia and/or those unaware of hypoglycaemia were excluded, preventing the results from being generalizable to these populations.

“We call for universal funding of this life-changing technology for all people living with T1D across the world. Further work is underway to assess the cost-effectiveness of this technology,” Leelarathna said.

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