Effect of Insulin Dilution on Lowering Glycemic Variability in Pump-Treated Young Children with Inadequately Controlled Type 1 Diabetes

Home Use of Day-and-Night Hybrid Closed-Loop Insulin Delivery in Very Young Children: A Multicenter, 3-Week, Randomized Trial

OBJECTIVE

We aimed to assess the feasibility and safety of hybrid closed-loop insulin delivery in children with type 1 diabetes aged 1-7 years as well as evaluate the role of diluted insulin on glucose control.

RESEARCH DESIGN AND METHODS

In an open-label, multicenter, multinational, randomized crossover study, 24 children with type 1 diabetes on insulin pump therapy (median age 5 years [interquartile range 3-6] and mean ± SD HbA_1c 7.4 ± 0.7% [57 ± 8 mmol/mol] and total insulin 13.2 ± 4.8 units/day) underwent two 21-day periods of unrestricted living and we compared hybrid closed-loop with diluted insulin (U20) and hybrid closed-loop with standard strength insulin (U100) in random order. During both interventions, the Cambridge model predictive control algorithm was used.

RESULTS

The proportion of time that sensor glucose was in the target range between 3.9 and 10 mmol/L (primary end point) was not different between interventions (mean ± SD 72 ± 8% vs. 70 ± 7% for closed-loop with diluted insulin vs. closed-loop with standard insulin, respectively; P = 0.16). There was no difference in mean glucose levels (8.0 ± 0.8 vs. 8.2 ± 0.6 mmol/L; P = 0.14), glucose variability (SD of sensor glucose 3.1 ± 0.5 vs. 3.2 ± 0.4 mmol/L; P = 0.16), or the proportion of time spent with sensor glucose <3.9 mmol/L (4.5 ± 1.7% vs. 4.7 ± 1.4%; P = 0.47) or <2.8 mmol/L (0.6 ± 0.5% vs. 0.6 ± 0.4%; P > 0.99). Total daily insulin delivery did not differ (17.3 ± 5.6 vs. 18.9 ± 6.9 units/day; P = 0.07). No closed-loop-related severe hypoglycemia or ketoacidosis occurred.

CONCLUSIONS

Unrestricted home use of day-and-night closed-loop in very young children with type 1 diabetes is feasible and safe. The use of diluted insulin during closed-loop does not provide additional benefits compared with standard strength insulin.

Continuous subcutaneous insulin infusion: Special needs for children

Continuous subcutaneous insulin infusion (CSII) is a very common therapy for children with type 1 diabetes. Due to physiological differences they have other requirements for their insulin pump than adults. The main difference is the need for very low basal rates. Even though most available insulin pumps reach a high accuracy at usual basal rates, accuracy decreases for lower rates. In addition, the lowest delivered amount at 1 time is limiting the fine tuning of the basal rate as well as the option for temporary basal rates. Alarms in case of occlusions depend on accumulation of a certain amount of insulin in the catheter, and therefore the time until such an alarm is triggered is much longer with lower basal rates. Accordingly, the risk for hyperglycemia developing into diabetic ketoacidosis increases. The availability of bolus advisors facilitates the calculation of meal and correction boluses for children and their parents. However, there are some differences between the calculators, and the settings that the calculation is based on are very important. Better connectivity, for example with a system for continuous glucose monitoring, might help to further increase safety in the use of CSII in children. When selecting an insulin pump for a child, the features and characteristics of available pumps should be properly compared to ensure an effective and safe therapy.