Closed-loop insulin delivery improves time in range regardless of baseline HbA1c
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Use of a closed-loop insulin delivery system resulted in improvement in time in range for people with type 1 diabetes in all subgroups of baseline HbA1c, according to an analysis of the International Diabetes Closed-Loop Trial.
Past studies have shown improvement in the percentage of time spent with glucose in the range of 70 mg/dL to 180 mg/dL for those with type 1 diabetes who used an automated delivery system such as closed-loop technology.
The International Diabetes Closed-Loop Trial evaluated the FDA-approved Control-IQ technology on the t:slim X2 insulin pump (Tandem Diabetes Care). In this randomized controlled trial, there was no limit on HbA1c levels for the participants. Results showed use of the closed-loop system was associated with a greater time in range compared with sensor-augmented pump therapy.
Laya Ekhlaspour, MD, assistant professor in the division of pediatric endocrinology and diabetes in the department of pediatrics, Center for Academic Medicine, at Stanford University School of Medicine, and colleagues analyzed data from 168 participants aged 14 to 71 years who had type 1 diabetes for at least 1 year. Most of the participants were white and non-Hispanic, had private insurance, and had an annual household income more than $100,000. The participants were randomly assigned to closed-loop insulin delivery or sensor-augmented pump therapy, and a baseline HbA1c was recorded during their randomization visit.
The baseline HbA1c levels ranged from 5.4% to 10.6%.
Closed-loop insulin delivery led to an improvement of time in range in all subgroups. Those with an HbA1c less than 6.5% experienced a 4.4% reduction (3.6% during the day and 6.8% overnight), whereas those with an HbA1c greater than 8.5% had a 21.9% improvement (19.2% during the day and 30.4% overnight). Young adults and adolescents had the highest HbA1c levels.
Whereas previous studies reported poorer glycemic control in women with type 1 diabetes, this study showed no clear trend, according to the researchers.
The automated basal insulin adjustments during both the day and night likely reduced hypoglycemia and hyperglycemia, and the hourly automatic correction boluses corrected hyperglycemia during the day in compensation for missed meal boluses, according to the researchers. Missed meal boluses are a major challenge for people with diabetes with suboptimal glycemic control. One study demonstrated that two missed boluses resulted in a half-point rise in HbA1c, whereas four missed boluses resulted in a full 1% rise in HbA1c levels. Users of hybrid closed-loop systems are advised to administer meal boluses 10 minutes before eating.
In this study, the use of the closed-loop system was shown to be an effective means of reducing nighttime hypoglycemia while increasing the percentage of time spent in the target range. Participants with lower HbA1c levels reduced their overnight hypoglycemia by the greatest percentage, likely because of the closed-loop system’s automated basal insulin adjustment.
“The results of this analysis are a strong argument for not having restrictions on who should have access to this technology,” the researchers wrote. “Potential users should not be excluded because they have already achieved recommended HbA1c targets, or because they have high HbA1c levels. In fact, people having the most difficulty adhering to current diabetes treatment recommendations will have the greatest improvements in time in range by using this technology.” – by Allison Flynn Becker
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