Insulin pump settings ideal for maintaining glucose levels with artificial pancreas
BOSTON — A one-time update of insulin-delivery parameters using patient data was no more effective at regulating blood glucose levels than using a patient’s insulin pump settings to initialize the artificial pancreas system, according to study findings presented here.
In a randomized, crossover, multicenter study analyzing glucose control algorithms, researchers also found that the artificial pancreas was more effective in maintaining good blood glucose control than doing so manually, without the use of the fully automated closed-loop system.
Eyal Dassau , PhD , diabetes team research manager with The Doyle Group, and colleagues from the University of California, Santa Barbara, analyzed data from 37 adults with type 1 diabetes (18 women; mean age, 47 years; mean BMI, 28 kg/m²) enrolled at three clinical sites. Using open-loop outpatient data, researchers initialized insulin-delivery parameters. Participants underwent two 27-hour periods of closed-loop control (CLC) with either unchanged or initialized parameters for the Zone-Model Predictive Control (MPC) artificial pancreas, in random order. Researchers asked participants to follow their usual meal plan along with an unannounced exercise session. The primary outcome measure was the percentage of time spent in the target glucose range of 80 mg/dL to 140 mg/dL, compared between both CLC arms and the open-loop group.
The median time spent in the range of 80 mg/dL to 140 mg/dL was uniform: 39.7% in the group with unchanged parameters, 44.2% in the group with initialized parameters and 39.5% for open-loop participants.
Researchers noted that there were no differences in percent times in target ranges between the nominal and initialized CLC groups, but both nominal and initialized CLC yielded significant benefits over open loop for time spent in the hypoglycemic range (median, 1.34% and 1.37%, respectively, vs. 6.73% in open loop; P < .0001). There were no significant differences in time between groups spent in the hyperglycemic range.
At night, time spent in the target range was significantly shorter during either CLC arm than open loop, according to researchers.
“The algorithmic initialization of insulin parameters did not yield convincing improvements, but the conclusion that CLC, in particular Zone-MPC, irrefutably promotes tight glucose control strongly endorses the goal of an automated [artificial pancreas], the researchers wrote.” – by Regina Schaffer
Dassau E, et al. Abstract 225-OR. Presented at: American Diabetes Association’s 75th Scientific Sessions; June 5-9, 2015; Boston.
Disclosure: Dassau reports research support from Animas Corp., Dexcom Inc. and LifeScan Inc.