Artificial pancreas race heats up with new Medtronic ASPIRE data

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Last week we posted Part 1 of Medtronic's Artificial Pancreas study, this week we've provided you with study results.

The latest ASPIRE results showed that Threshold Suspend “reduced nocturnal hypoglycemia, without increasing glycated hemoglobin [HbA1c] values”, the authors of the NEJM study concluded. Change in HbA1c was the primary safety outcome – if levels had increased with the use of Threshold Control, this would have increased patients’ risk of long-term complications. The primary efficacy outcome was the area under the curve (AUC) for nocturnal hypoglycemic events – which measures the magnitude and duration of these events.

The study also found, in summary:

• The mean AUC for nocturnal hypoglycemic events was 37.5% lower in the Threshold Suspend compared with the control group;
• Nocturnal hypoglycemic events occurred 31.8% less frequently in the Threshold Suspend group than in the control group;
• The mean AUC for combined daytime and nighttime hypoglycemic events was 31.4% lower in the Threshold Suspend group than in the control group;
• There was no change in HbA1C in either group; and
• No serious adverse events occurred in the Threshold Suspend group.

Medtronic describes the Threshold Suspend technology as an “important step” towards a fully-automated artificial pancreas. However, this still appears to be some way from the market. The firm has previously told Clinica that the next step will be developing a “treat-to-target range”, which not only suspends insulin at low blood glucose levels, but administers insulin if levels are too high. After this the company will work towards an overnight closed loop, then a full closed loop system – the actual artificial pancreas.

A Medtronic spokesperson told Clinica that its second-generation product is “nearing commercialization in Europe”. The device “automatically suspends insulin delivery when glucose values are predicted to reach a low threshold and then resumes insulin delivery once those glucose levels recover”.

Closed loop study

The company has also just announced it has enrolled the first of around 85 patients in the Phase II Overnight Closed Loop Study, which it describes as a “key feasibility” trial in the path towards creating the artificial pancreas. The in-clinic study will evaluate a third-generation closed loop algorithm that is designed to automatically achieve a specified target glucose value throughout the night; it will also test Medtronic’s fault detection technology.

Medtronic anticipates that the trial will be completed by “summer 2014” and will report results sometime after that.

“Unlike other systems in development, this system – classified by the FDA as a Control-To-Target system – is a fully automated system that requires no interaction from the user (except for calibration of the continuous glucose monitoring system),” the spokesperson said.

“Going a step beyond systems that only manage blood glucose to a broad target range, this system automatically adjusts insulin delivery to achieve a specific glucose value, such as 120mg/dL.”

In-clinic ASPIRE

Last year, Medtronic reported results from 50 patients in an earlier, in-clinic phase of the ASPIRE trial, which showed a 19% reduction in the length of hypoglycemic episodes in patients using Threshold Suspend versus conventional insulin pump therapy (www.clinica.co.uk, 2 March 2012). The results were published in the March 2012 issue of Diabetes Technology & Therapeutics.