Combining flash glucose monitoring with an automated bolus calculator

Advanced carbohydrate counting, defined as the calculation of bolus insulin doses based on carbohydrate ratios and insulin sensitivity, has previously been shown to improve HbA_1c and treatment satisfaction compared with experience-based bolus dosing. This Danish study sought to assess whether use of an automated bolus calculator (ABC), alone or in conjunction with flash glucose monitoring, would improve glycaemic control and patient-reported outcomes compared with usual care, in people with type 1 diabetes who were naive to these technologies.

A total of 170 participants were randomised 1:1:1:1 to usual care (n=42), an ABC (n=41), flash monitoring (n=48) or ABC and flash combined (n=39). Blinded CGM data were assessed at baseline and after 6 months. Baseline characteristics were comparable across the treatment arms, with an overall median diabetes duration of 18 years, median HbA_1c of 65 mmol/mol (8.1%), mean BMI of 26.7 kg/m² and mean age of 47 years.

After 6 months, there was no significant difference in terms of time in range, time above range or time below range in any of the treatment groups compared with usual care. In the ABC+flash arm, there were significant improvements in glucose coefficient of variation (CV; by 11%) and in Diabetes Treatment Satisfaction Questionnaire scores (by 4 points). Treatment satisfaction was also significantly higher in the flash monitoring group compared with usual care.

Discontinuation rates were higher in the ABC arm (39%) compared with usual care (17%), flash alone (4%) and ABC+flash (10%). Notably, however, in the ABC+flash arm, one in three participants either discontinued or reduced their use of the ABC over time.

In conclusion, the combination of flash glucose monitoring with an ABC had limited benefits in people with type 1 diabetes, beyond small improvements in glucose CV and treatment satisfaction. Many users showed resistance to ABC use.

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