Officially it’s called the “Medtronic MiniMed 670G hybrid closed loop insulin delivery system.” But don’t let that mouthful hide its importance.
The device is breakthrough “artificial pancreas” technology representing a major leap toward the Holy Grail of automated blood-glucose control – the golden dream of people with type 1 diabetes ever since insulin’s discovery in 1921.
It explains the excitement generated by US Food and Drug Administration approval of the Medtronic device in late September, even if it won’t reach the marketplace until next spring.
“My phone hasn’t stopped ringing, and it’s not even available yet,” said Patrick McCarthy, a diabetic educator at the Center for Diabetes and Endocrinology at the University of Pittsburgh Medical Center, who helps people manage their diabetes. “Everyone under the sun has found my phone number.”
Developed by Medtronic in Los Angeles, the device combines two existing technologies – a continuous glucose monitor that automatically tests blood sugar and an insulin pump that provides a steady dose of fast-acting, basal insulin.
Key to the technology is a smart computer algorithm that allows the monitor and pump to communicate. For the first two weeks, it learns the patient’s unique blood-sugar profile to optimise the performance of the algorithm. After this learning period, a variable rate of insulin is released every five minutes, 24 hours a day, to keep the person’s blood-glucose levels consistently near a predefined target range, with ability to adjust for unexpected variations in blood-glucose levels.
The device does require “minimal input” of the user to boost insulin prior to meals, reduce it prior to exercise or make adjustments to high blood sugars, as needed. “Patients only need to enter mealtime carbohydrates, accept bolus correction recommendations, and periodically calibrate the sensor,” Medtronic said.
For now, the device is approved only for people with type 1 diabetes who are 14 years old and older. Alejandro Galindo, president of intensive insulin management for Medtronic’s Diabetes Group, said the company is working to expand the device’s labelling for children ages 2 to 6 and 7 to 14, along with other upgrades.
Its accuracy was verified during a recent clinical trial involving 124 patients, all with reasonably well-controlled HgA1C readings that averaged 7.4 percent, Galindo said. The normal range for A1C – which measures a two- to three-month average blood-sugar percentage level – is 4 percent to 6 percent. After three months, the average A1C was 6.9 percent, or half a percentage point lower while also reducing fluctuations in levels. The results were considered dramatic.
In an unusual twist, McCarthy said, such diabetes devices are covered by most private health-insurance providers but not Medicare.
Type 1 diabetes more typically is diagnosed in childhood but also can be diagnosed in adults 40 and younger. It is caused by an autoimmune attack on pancreatic beta cells, which produce insulin, resulting in insufficient levels of insulin to transform blood sugar into cellular energy. Historically requiring insulin injections with syringes, insulin is more common administered nowadays with insulin pens and pumps.
The normal blood-sugar range for people without diabetes is 70 to 99 mg/dL before meals with postprandial readings of under 140 mg/dL. The American Diabetes Association recommends that people with diabetes strive for 70 to 130 prior to meals and under 180 two hours after meals.
Failure to maintain healthy blood sugar levels can lead to heart and circulatory disease, kidney failure, blindness, limb amputations and neuropathy, among numerous other health problems.
Here’s the technological puzzle the algorithm must solve: Current glucose monitors actually test interstitial fluids just below the skin, with those levels reflecting blood-sugar levels on a time delay. Once insulin is released under the skin, it can take 30 minutes to more than an hour before it effectively lowers blood sugar.
So the algorithm must take those time lags into account, while monitoring whether blood sugar is rising or falling to set a dose level every five minutes. The goal is preventing high blood sugar levels (hyperglycemia), which in time lead to health complications, and dangerously low levels (hypoglycemia), which cause weakness, sweating and confusion and even unconsciousness and death. Hypoglycemia most often occurs while the person is sleeping.
The device showed particular advantages in preventing hypoglycemia.
In all, Galindo said, the Medtronic device when running in auto-mode eliminates “90 percent of the mental gymnastics” required to manage diabetes, which he said represents a significant improvement.
“We have to make sure the experience of every patient who chooses our therapy has the most ideal experience possible,” he said. “Anything less would be completely unacceptable to me.”
Sandra Sobel, clinical chief of endocrinology at UPMC Mercy, said the new technology offers a major advance for people with diabetes.
“This approval of the Medtronic device is one step closer to achieving the goal and profound impact of potentially making the management of diabetes less tedious, while also improving quality of life because of the need to be constantly in tune with your blood-glucose levels,” Sobel said. “So we’re clearly excited about advancements in diabetes technology whenever something comes through the pipeline.”
The Joslin Diabetes Research Foundation in Boston also described approval of the Medtronic device as “a life-changing breakthrough” and “landmark goal” that brings a new level of control and consistency to the difficult task of managing diabetes.
The Medtronic device represents the first of many.
A TypeZero Technologies device using “inControl” algorithm technology developed at the University of Virginia Center for Diabetes Technology uses a smart phone to co-ordinate a Dexcom continuous glucose monitor with any off-the-shelf insulin pump.
Boris Kovatchev, the centre’s founding director, said the system developed with Joslin Foundation help will undergo a large clinical trial in January with $12.7 million from the National Institutes of Health, with hope it can reach market in a year or so. He said the inControl system also would work equally well for people with type 2 diabetes.
Various other medical device companies are working to launch similar technology within the next three years, he said.
“Typically artificial pancreases do a better job in controlling diabetes than what people are doing on their own,” he said. “That’s confirmed by a number of studies including our own. It is the best option currently available.” –Pittsburgh Post-Gazette/TNS