Glucose Control with an Artificial-Pancreas System
Standard treatment for tight blood glucose control in patients with type 1 diabetes is intensive insulin therapy designed to prevent long-term complications. The use of insulin pumps, glucose sensors, or a combination of the 2 devices has been tested in several studies; the risk of hypoglycemia is still a concern with the use of all of the therapies currently available.
Because most cases of severe hypoglycemia occur at night, maintenance of nocturnal euglycemia is both important and challenging. Nocturnal hypoglycemia accounts for 75% of total hypoglycemic seizures in children and may, according to researchers, be associated with 6% of deaths in patients <40 years of age with type 1 diabetes.
Recent studies in hospitals have demonstrated that an artificial-pancreas system can improve glucose control and reduce nocturnal hypoglycemia. However, it is unknown whether those results can be replicated in settings outside the hospital.
Researchers recently conducted a multicenter, multinational, randomized, crossover trial to evaluate the safety and efficacy of the artificial-pancreas system in young persons with type 1 diabetes, with an aim of achieving a substantial reduction in nocturnal hypoglycemia with near-normal overnight glucose control. The study was conducted in a youth camp setting. The results were reported in the New England Journal of Medicine [2013;368(9):824-833].
Eligible patients were 10 to 18 years of age with at least a 1-year history of type 1 diabetes, insulin-pump therapy for at least 3 months, a glycated hemoglobin level of 7% to 10%, a body mass index below the 97th percentile for the patient’s age, and an ability to adhere to the trial instructions. Exclusion criteria were a concomitant disease, participation in another study, pregnancy, history of diabetic ketoacidosis or severe hypoglycemia within the past month, and the use of medications or the presence of other conditions that might influence metabolic control, compromise safety, or prevent participants from completing the study.
In 2 consecutive overnight sessions, the researchers randomly assigned 54 patients to receive treatment with the artificial-pancreas system on the first night and a sensor-augmented insulin pump (control) on the second night or to the reverse order of therapies on the first and second nights. The primary end points were the number of hypoglycemic events, the time spent with glucose levels <60 mg per deciliter (3.3 mmol/L), and the mean overnight glucose level for individual patients. Hypoglycemic event was defined as a sensor glucose value of <63 mg per deciliter (3.5 mmol/L) for at least 10 consecutive minutes.
On nights when the artificial-pancreas system was used, compared with nights when the sensor-augmented insulin pump was used, there were significant decreases in the number of episodes in which the glucose level was <63 mg per deciliter (7 vs 22) and in the time during which the level was <60 mg per deciliter (P=.003 and P=.02, respectively). There were no significant between-treatment differences in the median overnight glucose levels: 126.4 mg per deciliter with the artificial-pancreas system and 140.4 mg per deciliter with the sensor-augmented pump.
Analyses of prespecified secondary end points showed significant improvements in several measures of glycemic control and glucose variability with the artificial-pancreas system compared with the sensor-augmented pump. Total overnight insulin doses were significantly higher during nights when the artificial-pancreas system was used compared with the nights when the sensor-augmented pump was used, although basal insulin doses were not significantly different.
In conclusion, the researchers stated, “Patients at a diabetes camp who were treated with an artificial-pancreas system had less nocturnal hypoglycemia and tighter glucose control than when they were treated with a sensor-augmented insulin pump.”
