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ADA: Bionic Pancreas Effective in Reducing Glucose Over Multiple Days

An automated "bionic" pancreas that incorporates glucagon as well as insulin has shown improved blood glucose for five consecutive days in a study of patients with type 1 diabetes….

The "bionic-pancreas" device consists of a Dexcom continuous glucose monitor (CGM) connected by a custom hardware interface that displays the readings and insulin and glucagon doses; t:slim insulin pumps deliver insulin and glucagon, and an iPhone is used to run the control algorithm.

The device is being developed collaboratively between Steven J. Russell, MD, PhD, and colleagues at Harvard as well as a team led by Ed Damiano, PhD, from the department of biomedical engineering at Boston University.

The researchers presented their findings on adolescents in an oral presentation at the 74th American Diabetes Association (ADA) Scientific Sessions last week. The researchers also reported on a study of an additional 20 adults using the same system and a similar crossover trial design published June 15 in The New England Journal of Medicine.

In the random-order, cross-over study of 32 adolescents participating in a diabetes camp, participants underwent glycemic control with an automated bihormonal bionic pancreas for 5 days and then had 5 days of control care with an insulin pump. Plasma glucose (PG) levels measured by finger stick and CGM levels were compared in a blinded manner between the two study arms.

The mean PG level was 138±18 mg/dL (range, 101–185 mg/dL) with the bionic pancreas compared with 157±27 mg/dL (range 103–221 mg/dL) during the control period (P = .004).

The bionic pancreas reduced the mean frequency of treatments for hypoglycemia from once per 0.8 days to once per 1.6 days (P < .001) and increased time in the 70 to 180 mg/dL range (75.9±7.9 vs 64.5±14.1; P < .001) by CGM.

In the study of 20 adults, results were similar, with a mean plasma glucose level during the 5-day bionic-pancreas period of 138 mg/dL (range, 116–166 mg/dL), and percentage of time spent with plasma glucose levels below 70 mg/dL of 4.8%.

On days 2 through 5 when compared with control (comparison started on day 2 to allow time for adaptation of the bionic-pancreas system), mean glucose level on CGM was 133 mg/dL with the bionic pancreas, compared with 159 mg/dL with usual care (P < .001). The percentage of time with glucose levels below 70 mg/dL was 4.1% vs 7.3% (P < .001).

Among the adults, the differences between bionic-pancreas and control periods were larger at night, with mean CGM values of 126 vs 169 mg/dL (P < .002), the percentage of time below 70 mg/dL was 1.8% vs 6.2% (P = .01) and below 60 mg/dL was 0.4% vs 3.3% (P = .01). No severe hypoglycemic events were noted.

The authors point out that "currently available rapid-acting insulin analogues still have relatively slow absorption after subcutaneous injection, and the poor stability of currently available glucagon formations necessitated daily replacement of the glucagon in the pump with freshly reconstituted material." In addition, the system had to rely on wireless connectivity to the insulin and glucagon pumps, which was "not completely reliable." They conclude that, despite these challenges, "the use of the bihormonal bionic pancreas … resulted in better glycemic control than is possible with the current standard of care."

Stuart A. Weinzimer, MD, Associate Professor of Pediatrics (Endocrinology) at Yale University School of Medicine and Associate Clinical Professor of Nursing at Yale School of Nursing, who discussed several proof-of-concept trials of closed-loop systems at the ADA session noted that, within the last year, closed-loop insulin delivery systems have transitioned from hospital research units to the real-world setting. He added that, currently, studies still include a small number of patients, but the numbers are about to increase, and "would be extremely robust in determining the safety and efficacy of these devices."

Practice Pearls:
  • The mean PG level was 138±18 mg/dL (range, 101–185 mg/dL) with the bionic pancreas
  • The bionic pancreas reduced the mean frequency of treatments for hypoglycemia from once per 0.8 days to once per 1.6 days
  • The use of the bihormonal bionic pancreas resulted in better glycemic control than is possible with the current standard of care.

Russell SJ, El-Khatib FH, Sinha M, et al.Outpatient Glycemic Control with a Bionic Pancreas in Type 1 Diabetes [published online ahead of print June 15, 2014]. N Engl J Med. DOI: 10.1056/NEJMoa1314474.