Exploration of the Performance of a Hybrid Closed Loop Insulin Delivery Algorithm That Includes Insulin Delivery Limits Designed to Protect Against Hypoglycemia.
Hypoglycemia remains a risk for closed loop insulin delivery particularly following exercise or if the glucose sensor is inaccurate. The aim of this study was to test whether an algorithm that includes a limit to insulin delivery is effective at protecting against hypoglycemia under those circumstances.



An observational study on 8 participants with type 1 diabetes was conducted, where a hybrid closed loop system (HCL) (Medtronic™ 670G) was challenged with hypoglycemic stimuli: exercise and an overreading glucose sensor.



There was no overnight or exercise-induced hypoglycemia during HCL insulin delivery. All daytime hypoglycemia was attributable to postmeal bolused insulin in those participants with a more aggressive carbohydrate factor.



HCL systems rely on accurate carbohydrate ratios and carbohydrate counting to avoid hypoglycemia. The algorithm that was tested against moderate exercise and an overreading glucose sensor performed well in terms of hypoglycemia avoidance. Algorithm refinement continues in preparation for long-term outpatient trials.
1 Department of Endocrinology and Diabetes, Princess Margaret Hospital for Children, Perth, WA, Australia.|2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.|3 School of Paediatrics and Child Health, The University of Western Australia, Perth, WA, Australia.
Martin
M
de Bock
2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.
Julie
J
Dart
4 Medtronic Minimed, Northridge, CA, USA.
Anirban
A
Roy
2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.
Raymond
R
Davey
2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.
Wayne
W
Soon
2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.
Carolyn
C
Berthold
2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.
Adam
A
Retterath
4 Medtronic Minimed, Northridge, CA, USA.
Benyamin
B
Grosman
4 Medtronic Minimed, Northridge, CA, USA.
Natalie
N
Kurtz
1 Department of Endocrinology and Diabetes, Princess Margaret Hospital for Children, Perth, WA, Australia.|2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.|3 School of Paediatrics and Child Health, The University of Western Australia, Perth, WA, Australia.
Elizabeth
E
Davis
1 Department of Endocrinology and Diabetes, Princess Margaret Hospital for Children, Perth, WA, Australia.|2 Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia.|3 School of Paediatrics and Child Health, The University of Western Australia, Perth, WA, Australia.
Timothy
T
Jones
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001786:Blood Glucose / Q000032:analysis; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy*; D015444:Exercise; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000517:prevention & control*; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage*; D007332:Insulin Infusion Systems; D008297:Male; D055815:Young Adult
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin
closed loop; continuous glucose monitoring; hypoglycemia; type 1 diabetes