The device takes over the task of monitoring and regulating sugar levels in the blood. Every 5 minutes, a signal is sent wirelessly from a glucose monitor under the user’s skin to an iPhone app, giving their blood-sugar status. The app calculates the amount of insulin or glucagon needed to balance blood sugar, sending a signal to pumps carried by the user to administer the required dose via a catheter. Before eating, people can input data about the type and size of their meal.
The artificial pancreas performed well in hospital-based clinical trials in 2010. But the important test is whether it works in a real-world environment. In the latest study, 20 adults wearing the device were put up in a hotel for five days but were otherwise free to do as they chose, including eat in restaurants and go to the gym. Thirty-two young people, aged 12 to 20, were also monitored for five days at a summer camp for kids with diabetes. For both groups, the results with the bionic pancreas were compared with five days of the participants using their usual method of controlling the disease – pricking their finger to monitor glucose levels and using an insulin pump, that requires them to manually calculate the dosage.
“The device performed beyond our expectations, it did a wonderful job of controlling their blood sugar,” says Damiano. Both the highs and lows of sugar levels were better controlled than what the participants were able to do managing their own diabetes prior to the trial, he says.
That is important because as many studies have shown, the better you control your glucose, the closer it is to normal range, the longer you can stave off the long-term health complications of diabetes, says Damiano.
Panel A shows the superimposition of tracings of mean glucose levels on continuous monitoring at all 5-minute steps during the 5-day period in all 20 patients in the adult study during the period when they were wearing the bionic pancreas (black) and during the control period (red). Each tracing is surrounded by an envelope (of corresponding color) that spans 1 SD in either direction around the mean glucose level at each 5-minute step. The mean glucose level during the bionic-pancreas period was 137 mg per deciliter, as compared with 158 mg per deciliter during the control period. Panel B shows tracings for the 32 patients in the adolescent study. The mean glucose level during the bionic-pancreas period was 147 mg per deciliter, as compared with 158 mg per deciliter during the control period. The shaded areas at the bottom of the two panels show clinically significant levels of glucose, including less than 50 mg per deciliter, indicating hypoglycemia (pink); 70 to 120 mg per deciliter, indicating good control (green); and 121 to 180 mg per deciliter, indicating mild hyperglycemia (blue between white lines). To convert the values for glucose to millimoles per liter, multiply by 0.05551.
The study had a tremendous emotional impact on participants. “They got a glimpse of life without diabetes, and that is pretty profound,” he says. In many cases, the participants were reluctant to give the devices back, he says.
Anna Floreen participated in the adult arm of the study and blogged about her experience: “I went to Starbucks and ate a banana for breakfast without fear of not enough time having passed between [insulin injection] and food consumption and wondering whether or not the 20 minute brisk walk to work would drop my blood sugar in 2 hours!”
“It’s fantastic that research on the artificial pancreas is forging ahead, both in the US and in the UK,” says Alasdair Rankin, director of research at Diabetes UK, a charity which is supporting the development of a similar device with researchers at the University of Cambridge. “Clearly more work will be needed before these systems can be used independently at home as a routine treatment option, but there is now real hope that this technology has the potential to transform the lives of people with type 1 diabetes within a generation,” he says.
Damiano hopes that a series of longer trials starting this month and next year will lay the path for the device to be approved by the US Food and Drug Administration. With any luck, this may come to pass before his son heads off to college – in the autumn of 2017.
In two random-order, crossover studies with similar but distinct designs, we compared glycemic control with a wearable, bihormonal, automated, “bionic” pancreas (bionic-pancreas period) with glycemic control with an insulin pump (control period) for 5 days in 20 adults and 32 adolescents with type 1 diabetes mellitus. The automatically adaptive algorithm of the bionic pancreas received data from a continuous glucose monitor to control subcutaneous delivery of insulin and glucagon.
Among the adults, the mean plasma glucose level over the 5-day bionic-pancreas period was 138 mg per deciliter (7.7 mmol per liter), and the mean percentage of time with a low glucose level (less than 70 mg per deciliter [3.9 mmol per liter]) was 4.8%. After 1 day of automatic adaptation by the bionic pancreas, the mean (±SD) glucose level on continuous monitoring was lower than the mean level during the control period (133±13 vs. 159±30 mg per deciliter [7.4±0.7 vs. 8.8±1.7 mmol per liter], P less than 0.001) and the percentage of time with a low glucose reading was lower (4.1% vs. 7.3%, P=0.01). Among the adolescents, the mean plasma glucose level was also lower during the bionic-pancreas period than during the control period (138±18 vs. 157±27 mg per deciliter [7.7±1.0 vs. 8.7±1.5 mmol per liter], P=0.004), but the percentage of time with a low plasma glucose reading was similar during the two periods (6.1% and 7.6%, respectively; P=0.23). The mean frequency of interventions for hypoglycemia among the adolescents was lower during the bionic-pancreas period than during the control period (one per 1.6 days vs. one per 0.8 days, P less than 0.001).
As compared with an insulin pump, a wearable, automated, bihormonal, bionic pancreas improved mean glycemic levels, with less frequent hypoglycemic episodes, among both adults and adolescents with type 1 diabetes mellitus.