Randomized Trial of the Insulin-Only iLet Bionic Pancreas for the Treatment of Cystic Fibrosis- Related Diabetes

Abstract

Objective: Cystic fibrosis-related diabetes (CFRD) affects up to 50% of adults with cystic fibrosis and adds significant morbidity and treatment burden. We evaluated the safety and efficacy of automated insulin delivery with the iLet bionic pancreas (BP) in adults with CFRD in a single-center, open-label, random-order, crossover trial.

Research design and methods: Twenty participants with CFRD were assigned in random order to 14 days each on the BP or their usual care (UC). No restrictions were placed on diet or activity. The primary outcome was the percent time sensor-measured glucose was in target range 70-180 mg/dL (time in range [TIR]) on days 3-14 of each arm, and key secondary outcomes included mean continuous glucose monitoring (CGM) glucose and the percent time sensor-measured glucose was in hypoglycemic range <54 mg/dL.

Results: TIR was significantly higher in the BP arm than the UC arm (75 ± 11% vs. 62 ± 22%, P = 0.001). Mean CGM glucose was lower in the BP arm than in the UC arm (150 ± 19 vs. 171 ± 45 mg/dL, P = 0.007). There was no significant difference in percent time with sensor-measured glucose <54 mg/dL (0.27% vs. 0.36%, P = 1.0), although self-reported symptomatic hypoglycemia episodes were higher during the BP arm than the UC arm (0.7 vs. 0.4 median episodes per day, P = 0.01). No episodes of diabetic ketoacidosis or severe hypoglycemia occurred in either arm.

Conclusions: Adults with CFRD had improved glucose control without an increase in CGM-measured hypoglycemia with the BP compared with their UC, suggesting that this may be an important therapeutic option for this patient population.

Graphical abstract

Figure 1

Distribution of mean percentage of TIR in the primary outcome, sensor-measured glucose target of 70–180 mg/dL and in the sensor-measured hypoglycemia of <54 mg/dL. The mean TIR for each participant on days 3–14 in the UC arm is shown with red circles on the left and is connected to the corresponding mean TIR on days 3–14 in the BP arm on the right. The diameter of each circle is proportional to the median percentage of time in sensor-measured hypoglycemia <54 mg/dL, with larger circles indicating greater time in the hypoglycemic range. The solid red line represents the mean across all participants. The dashed line represents the individual TIR therapy goal (70%) recommended by the ADA for people with type 1 diabetes.

Figure 2

Mean CGM glucose profiles according to time of day during the UC and BP arms. The mean CGM glucose profiles for all participants are shown from 12:00 a.m. to 12:00 a.m. in the UC and BP arms. The thicker lines indicate the mean, while the dashed lines bound the IQRs. The black dashed lines bound the target glucose range between 70 and 180 mg/dL.