In the Journals

Glucose control unchanged by single open-loop setting adjustment in type 1 diabetes

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August 19, 2015

In patients with type 1 diabetes, a single individualized algorithmic adjustment of open-loop settings does not appear to affect glucose control over a relatively short period of time, according to recent findings.

In the outpatient, randomized crossover clinical trial, Francis J. Doyle III, PhD, of the University of California, Santa Barbara, and colleagues evaluated 37 adults aged 21 to 65 years with type 1 diabetes at three clinical sites to determine the effects of a one-time algorithmic adjustment of basal rate and insulin-to-carbohydrate ratio open-loop setting on closed-loop control.

Participants had diabetes for at least 1 year, had been undergoing insulin pump treatment for at least 6 months and had an HbA1c of 10%. Insulin pump settings were exposed to the possibility of a one-time adjustment in algorithm based on 1 week of outpatient open-loop data collection for each participant. This data collection included pump, glucometer and subject diary.

Participants underwent two 27-hour intervals of closed-loop control sessions conducted in random order; the researchers used either unchanged (control) or algorithmic-adjusted basal rate and carbohydrate settings (adjusted) to commence the zone-MPC artificial pancreas controller.

The study’s primary outcome measure was time in the glucose range of 80 mg/dL to 140 mg/dL compared between the two groups.

Researchers found that of the 32 participants who completed the study, the median time in closed-loop control was 25.3 hours. The median time in the target glucose range was comparable between the two groups (39.7% control group; 44.2% adjusted group).

In both groups of closed-loop control, participants demonstrated minimal time spent in hypoglycemia (< 70 mg/dL). No significant differences were found for time spent above 140 mg/dL.

“We have demonstrated that neither the primary nor the secondary outcome variables differed between the two approaches to insulin parameter initialization preceding [closed-loop control],” the researchers wrote. “Furthermore, it is noteworthy that during the nocturnal period, hypoglycemia was very low overall and did not occur for some subjects with both [closed-loop control] approaches.” – by Jennifer Byrne

Disclosure: Doyle reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.