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Type 1 diabetics, who run the risk of dangerously low blood sugar, may be a step closer to getting help from a crude artificial pancreas device that can read blood sugar levels and automatically turn off the flow of insulin after a clinical trial showed the device is safe.
The long-awaited results of the clinical trial may pave the way for US approval of the device, made by Medtronic, which already sells insulin pumps with an automatic shutoff feature in 50 countries outside the United States. The feature is meant to guard against delivering insulin to diabetics if their blood sugar is already too low.
As many as 3 million Americans have type 1 diabetes, in which the immune system destroys cells in the pancreas that make insulin.
Type 1 diabetics must monitor their blood sugar and take insulin several times a day. Too little insulin can cause high blood sugar, increasing the risk of long-term complications such as eye damage, kidney failure and heart disease. But too much insulin can cause blood sugar to drop too low, causing hypoglycaemia, which can result in seizures, unconsciousness, brain damage and death.
US regulators have refused to allow insulin pumps with an automatic shutoff feature on the US market without a large, carefully controlled clinical trial proving they are safe.
The latest study, known as ASPIRE, which tested the system in 247 people with diabetes in their homes, offered the proof.
It showed the device reduced the amount of time and the duration that a diabetic's blood sugar fell below a certain threshold -- a measure known as area under the curve -- by 37.5%. The device reduced the overall number of low blood sugar episodes by 31.8%, compared to diabetics using an insulin pump without the shutoff feature.
The findings were published online on Saturday in the New England Journal of Medicine and presented at the American Diabetes Association meeting in Chicago.
Dr Francine Kaufman, vice president of global medical affairs for Medtronic's diabetes business, said the study showed that shutting off the flow of insulin mimics what happens in healthy people in response to low blood sugar.
Kaufman, a paediatric endocrinologist who still has an active practice in Los Angeles, said the device is intended to help diabetics who may find themselves in a situation where they cannot help themselves.
"Many of my patients are 3 years old. So, if mom is not around, they don't know how to do this on their own," she said. "We're going to take that and automate it for them."
Dr Richard Bergenstal, of the International Diabetes Center at Park Nicollet Health Services in Minneapolis, the study's lead author, highlighted the study's findings."That is a significant reduction in the duration and severity of low blood sugar," he told a news briefing at the diabetes meeting.
Holy grail
Diabetes advocates, researchers and medical device companies for decades have spoken wistfully about the "holy grail" of an artificial pancreas, a complex system of pumps and sensors aimed at automating the complex care and treatment of type 1 diabetes by mimicking the function of a real pancreas.
The Medtronic device is decidedly not that. But it is the first device before the US Food and Drug Administration to detect dangerous blood sugar levels and automatically take action to correct it.
"The study results are important as we continue to move toward our goal of developing a fully automated system, or artificial pancreas, that will one day require very minimal interaction from the patient," Medtronic's Kaufman said.
In designing the study, researchers had to find a population of patients who were especially prone to having hypoglycaemia at night. Bergenstal said as many as 320 people tried to enrol in the study, but only 247 qualified.
Spears Mallis, a 34-year-old administrator for the Longstreet Cancer Center in Gainesville, Georgia, was one. Mallis, an avid runner, has had type 1 diabetes for almost 17 years. For the past 16 or so, he has used an insulin pump, often pared with a continuous glucose monitor, to keep track of his blood sugar and deliver a steady flow of insulin.
But Mallis still suffers from occasional bouts of hypoglycaemia, which were especially disturbing when he had a job that required him to travel. Like many in the diabetes community, Mallis was aware of efforts several years ago by the Juvenile Diabetes Research Foundation and others to push the FDA to set guidelines for approving the Medtronic device. Some had even hoped the agency would allow these devices on the US market without additional testing.
But in 2011, the FDA made clear the company would need a clinical trial, and Mallis was on board. During the three-month trial, Mallis said the suspend device kicked in several times.
"In one of my races, it went off and I had it go straight to suspend."
He said the device's alarm feature was loud enough to wake his wife, but there were times he would sleep through it.
"After you have had type 1 diabetes for a while, your senses become lessened for feeling low blood sugar."
Mallis said the device would stop the flow of insulin until he woke and took
action himself. His experience was typical. Bergenstal said for many
individuals, the device was suspended for the full two-hour maximum, despite the
alarm.
"The study was also designed to see if cutting off insulin for this period would cause insulin to 'rocket back up'," Bergenstal said.
Drifted back to normal
But at the end of the two-hour period, it just "gradually drifted back up into the normal range", he said.
The study also showed the device had no impact on a measure of long-term control of blood sugar called A1c.
Kaufman said Medtronic has presented the study results to the FDA and received an approvable letter for its next-generation pump device that includes the feature, meaning the device can be approved, provided the company meets certain conditions.
Chief Executive Omar Ishrak has said he expects device approval during the current calendar year.
"We are just going back and forth on overall quality issues. We're working very collaboratively with FDA to work through some of the issues," Kaufman said.
Meanwhile, the company and its rivals, including Johnson & Johnson's Animas unit, are working on next-generation devices that add more automated features.
On Friday, the company presented results at the diabetes meeting on a study of a system designed to predict when diabetics are heading for a dangerous low and take pre-emptive action by decreasing the amount of insulin the pump delivers.
The night-time study of 20 adults with type 1 diabetes showed the software control program helped people stay within a target range for 90% of the time.
Ramakrishna Venugopalan, director for research and development at Animas, sees the development of an artificial pancreas as a step-wise process, in which products begin to automate more and more of the functions now managed by patients.
The company this month won approval for another feasibility study, its third in three years.
Venugopalan still can't say when a fully automated artificial pancreas will
be available, but adds, "I don't think this is a pipe dream."
