A Boise-based engineer played a key role in the development of a redesigned insulin delivery system approved by the U.S. Food and Drug Administration in April.
Lou Lintereur used his aerospace engineering training to help develop the control algorithm for MiniMed 780G system from Medtronic Diabetes. The system is the first insulin pump with meal detection technology offering five-minute automatic adjustments and corrections and is an upgrade from earlier models.
Lintereur worked with a specialized team to develop the closed loop control algorithm.
“That algorithm is like the brains of the system that does the control. I was a lead of the overall system development, but on the algorithm design I was a collaborator on a team with Anirban Roy and Benyamin Grosman to create the algorithm and then transfer it into the software.”
“The 780G system is part of an evolution of systems that we’ve been developing over decades,” Lintereur said.
Medtronic started by developing devices such as insulin pumps and blood glucose sensors to manage diabetes therapy.
“But it was all a very manual process,” Lintereur said. “If you wear an insulin pump you need to control the rate of insulin delivery. If you have anything with carbohydrates, that’s going to make your blood sugar rise, and you would have to program an extra dose, a bolus of insulin to keep your blood sugar under control.”
This system offers more automated deliveries, capable of measuring blood glucose as often as every five minutes through the sensor and adjusting the insulin dosage automatically through software tied to the insulin pump.
“You have the insulin pump in your pocket or on a belt that has the control software, a blood glucose sensor you typically wear on the back of your arm and the infusion set, which inserts under the skin at the waist to deliver the insulin,” he said. The new technology extends the life of the latter from every two-three days to seven days. Patients must refill the insulin reservoir every few days and replace the sensor once a week.
The pump delivers the basal insulin dose for in-between meals or overnight requirements. Bolus doses of insulin are provided for real time, “so if you eat a meal on top of your basal you need to give extra insulin to manage the carbohydrates for the meal,” Lintereur said.
Their earlier system, the 670G, offered that hybrid closed loop automation, providing the basal dose.
“It tremendously improved the lives of patients with Type 1 diabetes. It took a lot of that burden of therapy away from the patients. We built a lot of safety features into the system to make sure that if something went wrong with the sensor, we weren’t going to give them too much or too little insulin.”
Patients received frequent alerts from the system when glucose numbers fluctuated from safe levels. But they preferred not getting alerts in the middle of the night or other inconvenient times, as often occurred.
“We found that in almost all cases we didn’t have to give that alert. We tailored them to provide optimal safety without interrupting the patients.”
Beyond the alerts, the redesign was also based on patient feedback wanting better blood sugar control and more automation, leading to the 780G system, which won FDA approval April 21.
The improvements responded to patients’ desires to keep their glucose levels closer to non-diabetic levels. Those without diabetes will have a blood sugar reading of about 90-100 milligrams per deciliter (mg/dl) when fasting. With safety in mind, the first system was designed to target glucose levels at 120 mg/dl because, Lintereur said, “if your blood sugar gets too low you get a condition called hypoglycemia which can be very dangerous and even fatal to the patient.”
Lintereur said engineers like safety margins, even though doctors might consider a fasting level of 120 mg/dl to be pre-diabetic. That level, offered in the older model, was a one-size-fits-all.
“We found a way to lower that target glucose to as low as 100 mg/dl without sacrificing the safety of the system at that lower level.”
However, brisk exercise can cause blood sugar to drop, so the new system allows users to set a temporary target and raise it artificially to 150. That gives patients more of a cushion against hypoglycemia before exercising, he said.
Clinical studies were done at the device’s highest and lowest settings” just to make sure that no matter where you set it, you’re going to be safe.”
Other system features including display capability through smartphone apps, and connections to the cloud, allowing access for remote care partners.
“The combination of the lower set point, meal detection and the frequent correction boluses provides a revolutionary technology.”
The ultimate goal, Lintereur said, is the development of an artificial pancreas, “and we’re still working toward that.” The American Diabetes Association and an international consensus of endocrinologists indicate the goal is achieving blood sugar levels between 70 mg/dl and 180 mg/dl for 70 percent of the time.
“We target about 100 mg/dl so it’s kind of in between,” he said. In Europe, where the system has been available since 2020, the system is getting 80 percent time on target, “well exceeding the recommendations of the ADA and international consensus.”
Lintereur said Medtronic’s older system was the first to hit the 70 percent range. Hitting the 80 percent time range with the new system “is a very big step.”
The company will begin accepting pre-orders May 15, with system availability in late June.
Medtronic’s diabetes division is headquartered in Northridge, CA, with global headquarters in Dublin. Lintereur works remotely from Boise. He earned his master’s degree in aerospace engineering with a subdiscipline of control theory from MIT in 1996. An aerospace engineer for NASA, he transitioned to medical technology in 2007 while living in California.