Two hormones better than one for hypoglycaemia prevention with artificial pancreas

By Eleanor McDermid, Senior medwireNews Reporter

Artificial pancreas systems significantly improve glycaemic control in adolescents and adults with Type 1 diabetes, shows a head-to-head trial of single- and dual-hormone systems versus a conventional insulin pump.

And the findings, published in The Lancet Diabetes & Endocrinology, suggest that a dual-hormone system (insulin plus glucagon) might have the edge over a single-hormone system (insulin alone) in terms of reducing hypoglycaemia.

Researchers Ahmad Haidar (Institut de Recherches Cliniques de Montreal, Quebec, Canada) and team recruited 30 patients, of whom 10 were adolescents, with an average age of 14 years.

Before the start of the crossover trial, the team optimised basal insulin delivery rates and insulin-to-carbohydrate ratios for the participants’ conventional insulin pump therapy. Each 24-hour trial period was conducted in a research facility, but included social activities and exercise to mimic outpatient conditions.

During trial periods when they were using a conventional insulin pump, participants remained within target daytime plasma glucose concentrations 51% of the time, with the target range defined as 4.0 to 8.0 mmol/L, and 4.0 to 10.0 mmol/L for 2 hours after eating.

The single- and dual-hormone artificial pancreas systems both improved this significantly, to 62% and 63%, respectively, with no difference between the two systems.

Overnight, participants remained within the target range for 46%, 70% and 65% of the time with the conventional, single-hormone and dual-hormone systems, respectively, with the artificial pancreas systems again offering a significant improvement.

Participants rarely fell below the target range during the night, but the artificial pancreas systems produced a large reduction in the overall time spent below the target range, from 13.3% with the conventional pump to 3.1% with the single-hormone system and 1.5% with the dual-hormone system. The difference between the single- and dual-hormone systems was statistically significant.

There were a total of 52 hypoglycaemic episodes (<3•3 mmol/L with symptoms or <3•0 mmol/L without) during conventional pump use, falling to 13 and nine for the single- and dual-hormone systems, respectively. The corresponding numbers for episodes of exercise-induced hypoglycaemia were 12, three and four.

The researchers note that the amount of glucagon delivered by the dual-hormone system was very small: an average of 0.13 mg overall and 0.026 mg at night, with a median bolus size of 0.012 mg.

However, in a commentary accompanying the study, Steven Russell (Massachusetts General Hospital, Boston, USA) notes that “more liberal” delivery of glucagon might have been even more effective.

He says: “The true incremental value of glucagon will be shown in the unrestricted outpatient setting where the control system must cope with a greater variety and intensity of challenges to glucose stability.”

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