Three investigators presented positive data on hybrid closed loop systems of insulin delivery at the 76th Scientific Sessions of the American Diabetes Association, June 10–14, in New Orleans.
Bergenstal's Study of the Medtronic MiniMed 670G Pump for Home Use in Type 1 Diabetes
Richard M. Bergenstal, MD, an endocrinologist at the International Diabetes Center at Park Nicollet, Minneapolis, Minnesota, explained that he and colleagues evaluated the MiniMed 670G closed loop system to establish its safety for unsupervised use in patients with type 1 diabetes ≥14 years of age. The system included 4th-generation sensors and a control algorithm.
Patients calibrated the sensor periodically and gave mealtime and correction boluses as needed. A 2-week run-in (baseline) phase was followed by a 3-month study phase of the system at home and in supervised hotel settings for five nights followed by an optional continued-access program.
Data were available from 124 patients (55 male) with a mean age of 37.8 ± 16.46 years (n=30 age ≤21 years) and duration of diabetes 21.7 ± 13.65 years. Sensor glucose and hemoglobin A1c values from baseline and study phases were compared. Hybrid closed loop mode was used for a median 87.2% interquartile range 75.0% to 91.7%) of the time after first start.
Higher percentages of sensor glucose 71-180 mg/dL, lower percentages of sensor glucose ≤70 mg/dL, and lower percentages of sensor glucose ≤50 mg/dL were observed during 24 hours and at night (P< .001 for each) in the study phase vs baseline. Mean hemoglobin A1c decreased from 7.4 ± 0.9% to 6.9 ± 0.6% (P<.001). Sensor glucose variability measured by coefficient of variation decreased from 0.38 to 0.35 (P<.001).
No diabetic ketoacidosis, severe hypoglycemia, or serious device-related adverse event was observed during 12,389 patient-days. At study end, 99 patients entered the continued-access program.
O'Neal's Comparison of the Overnight Closed Loop Pump vs a Sensor-Augmented Pump with Low-Glucose Suspend in Patients with Type 1 Diabetes
David Norman O'Neal, MBBS, MD, an endocrinologist at St. Vincent's Hospital, Melbourne, Victoria, Australia, explained that an overnight closed loop pump and sensor-augmented pump with low-glucose suspend have not been compared.
Dr. O'Neal and colleagues conducted a randomized controlled crossover evaluation of the overnight closed loop system at home. Their system uses an Android phone as a platform to control insulin delivery by the Medtronic MiniMed 670G.
Sixteen adults (mean age 42.1 ± 9.6 years; hemoglobin A1c 7.3 ± 0.6%) and 12 adolescents (15.2 ± 1.6 years; hemoglobin A1c 7.8 ± 0.5%) with type 1 diabetes were assigned in random order to the overnight closed loop system (proportional integral derivative with insulin feedback algorithm Version 1.0; Medtronic) or the sensor-augmented pump with low-glucose suspend for 4 nights at home.
Adults and adolescents had the overnight closed loop system active for 90% of the time between 00:00-8:00 am. In adults, the primary endpoint of time in the target range of 72-144 mg/dL was greater with the closed loop system overnight and for the entire 24-hours. In adolescents, the overnight closed loop system decreased time in the hypoglycemic range overnight.
Overall, the number of symptomatic hypoglycemic episodes overnight was lower with the closed loop system than with the sensor-augmented pump with low-glucose suspend system (6 vs 23 symptomatic hypoglycemic episodes; P=.0016).
The closed loop system reduced glycemic variability (sensor glucose standard deviation) overnight. Adolescents using the sensor-augmented pump with low-glucose suspend system spent greater time in the target range overnight than adults (64.4 vs 44.5%; P=.003) and less time in the target range during the day (43.9 vs 53.0%; P=.04).
Hovorka's Study of a Closed Loop System in Inpatients with Type 2 Diabetes
Roman Hovorka, PhD, Principal Research Associate, Institute of Metabolic Science, University of Cambridge, UK, and colleagues evaluated the application of an automated fully closed loop insulin delivery system without meal bolusing in insulin-treated type 2 diabetes patients in the general ward.
In a randomized, controlled, parallel-design study, 24 adults with type 2 diabetes were randomized to receive either closed loop-directed subcutaneous delivery of insulin lispro (n=12) or conventional subcutaneous insulin therapy as per usual clinical guidelines with masked continuous glucose measurements (n=12) for a maximum period of 72-hours.
Participants consumed self-selected hospital meals and were matched for age (70 ± 12 vs 67 ± 13years), hemoglobin A1c (9.0 ± 2.7% vs 9.2 ± 2.0%), and body mass index (33.3 ± 8.2 vs 33.2 ± 8.2 kg/ m2). Usual insulin and sulphonylurea therapy were withheld from participants receiving the closed loop system.
In an intention to treat analysis, the proportion of time when sensor glucose was in target range [5.6-10.0 mmoL/L (100-180mg/dL)] was significantly higher during use of the closed loop system (P=.005). Time spent above target was significantly lower during use of the closed loop system (P=.023).
A trend toward reduced mean sensor glucose during use of the closed loop system was observed (P=.057). Time spent below target was low and comparable, as were capillary glucose readings below 3.9mmoL/L (3 vs 5 events).
Bergenstal RM, O'Neal DN, Hovorka R. Closing the Loop on Insulin Management - Are We There Yet?. ADA 2016: 76th Scientific Sessions of the American Diabetes Association, June 10-14, New Orleans, LA.
R.M. Bergenstal: Advisory Panel; Speaker; Boehringer Ingelheim Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Eli Lilly and Company, Johnson & Johnson, Novo Nordisk, Inc., Roche Pharmaceuticals, sanofi-aventis, Takeda Pharmaceutical Company, Ltd., Halozyme Therapeutics. Consultant; Speaker; Boehringer Ingelheim Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Eli Lilly and Company, Halozyme Therapeutics, Johnson & Johnson, Novo Nordisk, Inc., Roche Pharmaceuticals, sanofi-aventis, Takeda Pharmaceutical Company, Ltd.. Research Support; Speaker; Boehringer Ingelheim Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Eli Lilly and Company, Halozyme Therapeutics, Johnson & Johnson, Novo Nordisk, Inc., Roche Pharmaceuticals, sanofi-aventis, Takeda Pharmaceutical Company, Ltd..
D.N. O'Neal: Advisory Panel; Author; Medtronic, Inc., Abbott Diabetes Care Inc., Firefly Bioworks, Inc. Research Support; Author; Medtronic, Inc., Sanofi U.S.. Speaker's Bureau; Author; Medtronic, Inc., Sanofi U.S., Novo Nordisk Inc.
R. Hovorka: Advisory Panel; Author; Eli Lilly and Company. Consultant; Author; B. Braun Melsungen AG, Sanofi-Aventis Deutschland GmbH, Profil Institute for Clinical Research, Inc.. Speaker's Bureau; Author; Medtronic MiniMed, Inc., Eli Lilly and Company, B. Braun Melsungen AG, Novo Nordisk A/S.