medwireNews: Home use of day and night hybrid closed-loop insulin delivery using the Cambridge model predictive control algorithm is feasible in children aged 1–7 years with type 1 diabetes, researchers report.
“Results of the current study are consistent with observations in older children, adolescents, adults, and pregnant women about safety and efficacy of closed loop therapy using Cambridge model predictive control,” say Roman Hovorka (University of Cambridge, UK) and colleagues.
They add that their findings confirm “the robustness of our model predictive algorithm and [support] the application of our closed loop systems across a broad range of people with type 1 diabetes including preschool children.”
The study included 23 children (median age 5 years) undergoing insulin pump treatment who took part in two 3-week treatment periods – one involving closed loop with diluted insulin (20 units/mL) and the other closed loop with standard strength insulin (100 units/mL) – in a random order. Real-time continuous glucose monitoring was used throughout the study, and after a 1–2 hour training clinic visit participants remained in free-living settings at home or at school/nursery.
Diluted insulin was included in this study in light of “[a]necdotal reports [suggesting] that the use of diluted insulin in young children may be beneficial to decrease glycemic variability, reduce occurrence of unexplained hyperglycemia, and reduce infusion set failures,” explain the investigators.
As reported in Diabetes Care, the average proportion of time spent in the target blood glucose range of 3.9–10 mmol/L was similar during closed-loop delivery with diluted insulin compared with standard insulin, at 72% and 70%, respectively.
There was also no significant difference in average glucose levels (8.0 vs 8.2 mmol/L), glucose variability, or the proportion of time spent with glucose levels below 3.9 mmol/L (4.5 vs 4.7%) between the diluted and standard insulin groups, indicating “[n]o benefits associated with the use of diluted insulin” in the closed-loop system.
The researchers did observe a “modest but statistically significant reduction” in the amount of bolus insulin required when diluted insulin was used (10.4 vs 11.8 units/day), which they attribute to “slightly lower glucose levels during closed loop with diluted insulin resulting in a reduced amount of insulin delivered as correction boluses.”
Hovorka and colleagues note that the “closed loop system performed particularly well overnight,” with sensor glucose levels in the target range 77–80% of the time, and average overnight glucose levels of 7.6–7.9 mmol/L. The corresponding daytime measurements were 67–68% and 8.2–8.3 mmol/L.
“Because of this favorable nocturnal performance, hybrid closed loop systems may be particularly appealing to families and caregivers of young children with type 1 diabetes,” say the study authors.
They report that the intervention had a favorable safety profile, with no cases of severe hypoglycemia or diabetic ketoacidosis occurring during the study.
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