Artificial pancreas improves on insulin pump therapy in Type 1 diabetes

By Sally Robertson, B.Sc.Feb 15 2013

The dual-hormone closed-loop delivery system, a type of artificial pancreas, could offer significant advantages over conventional insulin pump therapy in Type 1 diabetes patients, report researchers.

Compared with continuous subcutaneous insulin infusion, the system improved glycemic control and reduced the risk for hypoglycemia in a cohort of 15 patients who were monitored during a 15-hour hospital visit that included an overnight stay, say Ahmad Haidar (McGill University, Montreal, Quebec, Canada) and colleagues.

During the night, closed-loop delivery reduced the rate of hypoglycemia more than 20 fold, compared with standard insulin infusion.

As reported in the Canadian Medical Association Journal, patients treated with the closed-loop system had their glucose regulated with subcutaneous insulin infusion combined with subcutaneous miniboluses of glucagon delivered by two infusion pumps, as determined by an advanced mathematical algorithm.

Patients who received subcutaneous insulin infusion only (controls), had access to their finger stick glucose measurement and adjusted their insulin delivery according to the carbohydrate content of their evening meal and bedtime snack.

During visits involving the closed-loop delivery, plasma glucose levels were in the target range (4-10 mmol/L between hours 1600 and 2300, 4-8 mmol/L between 2300 and 0700) a median of 70.7% of the time, compared with 57.3% of the time during control visits.

Closed-loop delivery significantly decreased the proportion of time spent in hypoglycemia compared with conventional treatment, at a respective 0.0% versus 10.2% when hypoglycemia was defined as plasma glucose levels of less than 4.0 mmol/L, and 0.0% versus 2.8% for levels of less than 3.3 mmol/L.

During the night, the percentage of time spent in the target range for plasma glucose levels was significantly higher with closed-loop delivery than with conventional treatment, at 72.0% versus 45.8%.

Furthermore, 45 (12.3%) of the overnight plasma glucose measurements were at concentrations below 4.0 mmol/L during control visits, compared with only two (0.5%) measurements during closed-loop delivery - a 22.5-fold reduction.

"Hypoglycemia remains underestimated, with up to 60% of events going unrecognized," note Haidar et al. "These systems have the potential to substantially improve the management of diabetes and the safety of patients."

"Patients with hypoglycemia unawareness might benefit most from this technology," they add.

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