Abstract
Dear Editor,
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An otherwise well female infant was diagnosed with type 1 diabetes at 7 months, based on clinical presentation and positive IA2 antibodies. Early management with multiple daily injections (using insulin bolus calculator with carbohydrate counting) was complicated by low insulin requirement (0.8 U/[kg·day], total daily dose [TDD] 5.5 U), as well as frequent hyperglycemia and hypoglycemia. Within 2 weeks of diagnosis, she was started on diluted insulin aspart (1:5, diluted at home with normal saline using aseptic technique) and Dexcom G5™ continuous glucose monitoring (CGM). Several weeks later, she was commenced on a Medtronic 670G pump with Medtronic Guardian Link 3 CGM. Initial insulin pump settings were based on 80% of TDD, with 40% basal and utilizing the 400 rule for carbohydrate ratio and 100 rule for insulin sensitivity. She spent 4 weeks in manual mode before activating auto mode. Table 1 demonstrates improvement in all parameters over time, with time in range (TIR) over 70% within 6 weeks of commencing auto mode. An upgrade to the Medtronic 770G pump was undertaken 6 months after diagnosis with auto mode successfully recommenced 1 week later and TIR remaining >70%. Insulin dilution was changed to 1:2.5 8 months after commencing insulin pump therapy as bolus doses were increasing and there was parental perception of delayed resolution of hyperglycemia postcorrection bolus. Apart from initial teething problems with CGM correlation with dextrostix, she had one infusion site infection requiring oral antibiotics, but no other complications or insulin pump set failures. The family report that in addition to improving glycemia, the use of hybrid closed loop with dilute insulin has made their child's diabetes easier to control and reduced the day-to-day burden of disease. In particular, the family saw excellent glycemic control overnight, along with decreased awakenings for both parents and infant.
Table 1.
Active insulin time used throughout: 3 h.
Calculated over 2-week period.
Total daily dose of insulin.
On reducing insulin doses over this time.
Multiple daily injections.
Hybrid closed loop.
Time in range.
Coefficient of variation.
Glucose management indicator.
NA, weight not available; TIR, time in range.
Managing diabetes in very young children is often difficult, requiring creativity and flexibility due to unpredictable carbohydrate intake and activity levels, poor hypogylcemia awareness, increased variability of insulin requirements, and low insulin doses. 1,2 Although insulin pumps and hybrid closed loops can be beneficial, there are additional obstacles encountered when looking to use these technologies in this age group, including that available insulin pumps are unable to give very small doses with accuracy. 1 Hybrid closed loop therapy systems, the use of which has been shown to improve glycemic control and psychosocial outcomes in older children, 2 often have a minimum TDD of insulin required (8 U for the Medtronic(®)670G Auto Mode system).
Many of these difficulties can theoretically be overcome by using diluted insulin. 1 The use of diluted insulin is well described in infants and young children in both multiple daily injection regimes and insulin pumps alone. 1,3 Diluted insulin has been shown to improve glycemic control and variability in children with low TDDs of insulin in those as young as 1.3 years of age. 2,4
Two studies 3,5 have demonstrated the short-term safety of utilizing dilute insulin in hybrid closed loop systems in younger age groups, but these studies did not include children <1 year of age and looked at these systems either overnight or with short-term use only (up to 21 days). In addition to safety, one of these studies demonstrated reduced rates of hypoglycemia and individual variability with dilute compared with standard insulin in children aged 3–6 years. 3 To our knowledge, there has been no research looking at the safety or efficacy of these systems in infants <12 months of age or with TDDs of insulin <8 U, and no studies extending beyond a few weeks.
Comparison of 14-day average glycemic control in manual and auto mode.
This letter reports the first real-world use of hybrid closed loop insulin pump technology using dilute insulin in a child <1 year, demonstrating improvement in diabetes control as each intervention was introduced; stepwise improvement was seen in TIR and glucose variability with dilution of insulin, introduction of insulin pump therapy, and commencement of hybrid closed loop. These improvements have been sustained for >6 months, with observed and reported parental satisfaction.
This case demonstrates the safe and effective use of these emerging diabetes technologies in infants. In addition, with the use of diluted insulin, it suggests a potential solution for technologies that require a minimum TDD of insulin. Given the complexity of managing insulin-dependent diabetes in young infants, we hope this report will lead to further research and clinical use of new diabetes technologies in this group.
Consent
Verbal and written consent have been obtained from the parents of the patient.
Footnotes
Author Disclosure Statement
No competing financial interests exist.
Authors' Contributions
All listed authors contributed substantially to the article and have approved the final version. J.L.S., K.A.N., and P.P. wrote, reviewed, and edited the article.
Funding Information
No funding was received for this article.