Software Bug Results In Insulin Pump Injuries, Spurs Recall

May 11, 2024 by Dan Maloney 24 Comments

Managing Type 1 diabetes is a high-stakes balancing act — too much or too little insulin is a bad thing, resulting in blood glucose levels that deviate from a narrow range with potentially dire consequences on either side. Many diabetics choose to use an insulin pump to make managing all this easier, but as a recent recall of insulin pump software by the US Food and Drug Administration shows, technology isn’t foolproof.

Thankfully, the recall is very narrow in scope. It’s targeted at users of the Tandem t:slim X2 insulin pump, and specifically the companion application running on iOS devices. The mobile app is intended to run on the user’s phone to monitor and control the pump. The pump itself is a small, rechargeable device that users often keep on their belt or tucked into a pocket that delivers a slow, steady infusion of insulin during the day, plus larger bolus doses to compensate for meals.

But version 2.7 of the t:connect mobile app can crash unexpectedly, and on iOS devices, that can lead to the OS continually relaunching it. Each time it does this, the app tries to reconnect with the pump via Bluetooth, which eventually runs down the battery in the pump. Once the battery is dead, no more insulin can be delivered, potentially leading to a condition called hyperglycemia (“hyper” meaning an excess, “gly” referring to sugar, and “emia” meaning presence in blood — excess sugar in the blood.)

Untreated hyperglycemia can progress to a much more serious state called diabetic ketoacidosis, which can lead to coma and death. Thankfully, nobody has suffered that fate from this bug, but the FDA has received over 200 reports of injuries, hence the recall. Tandem sent out a notice to all affected customers back in March to update their apps, but it’s still possible that some users didn’t get the message.

Apart from the human cost of this bug, there’s a lesson here about software design and unintended consequences. While it intuitively seems like a great idea to automatically relaunch a crashed app, especially one with a critical life-safety function, in hindsight, the better course might have been to just go into a safe mode and alert the user with an alarm. That’s a lesson we’ve learned by exploring space, and it seems to apply here as well.

Images: AdobeStock, Tandem Diabetes

Implant Fights Diabetes By Making Insulin And Oxygen

October 10, 2023 by Dan Maloney 13 Comments

Type 1 diabetes remains a problem despite having an apparently simple solution: since T1D patients have lost the cells that produce insulin, it should be possible to transplant those cells into their bodies and restore normal function. Unfortunately, it’s not actually that simple, and it’s all thanks to the immune system, which would attack and destroy transplanted pancreas cells, whether from a donor or grown from the patient’s own stem cells.

That may be changing, though, at least if this implantable insulin-producing bioreactor proves successful. The device comes from MIT’s Department of Chemical Engineering, and like earlier implants, it relies on encapsulating islet cells, which are the insulin-producing cells within the pancreas, inside a semipermeable membrane. This allows the insulin they produce to diffuse out into the blood, and for glucose, which controls insulin production in islet cells, to diffuse in. The problem with this arrangement is that the resource-intensive islet cells are starved of oxygen inside their capsule, which is obviously a problem for the viability of the implant.

The solution: electrolysis. The O₂-Macrodevice, as the implant is called, uses a tiny power-harvesting circuit to generate oxygen for the islet cells directly from the patient’s own interstitial water. The circuit applies a current across a proton-exchange membrane, which breaks water molecules into molecular oxygen for the islet cells. The hydrogen is said to diffuse harmlessly away; it seems like that might cause an acid-base imbalance locally, but there are plenty of metabolic pathways to take care of that sort of thing.

The implant looks promising; it kept the blood glucose levels of diabetic mice under control, while mice who received an implant with the oxygen-generating cell disabled started getting hyperglycemic after two weeks. What’s really intriguing is that the study authors seem to be thinking ahead to commercial production, since they show various methods for mass production of the cell chamber from standard 150-mm silicon wafers using photolithography.

Type 1 diabetics have been down the “artificial pancreas” road before, so a wait-and-see approach is clearly wise here. But it looks like treating diabetes less like a medical problem and more like an engineering problem might just pay dividends.

Open-Source Insulin: Biohackers Aiming For Distributed Production

August 23, 2021 by Dan Maloney 74 Comments

When you’ve got a diabetic in your life, there are few moments in any day that are free from thoughts about insulin. Insulin is literally the first coherent thought I have every morning, when I check my daughter’s blood glucose level while she’s still asleep, and the last thought as I turn out the lights, making sure she has enough in her insulin pump to get through the night. And in between, with the constant need to calculate dosing, adjust levels, add corrections for an unexpected snack, or just looking in the fridge and counting up the number of backup vials we have on hand, insulin is a frequent if often unwanted intruder on my thoughts.

And now, as my daughter gets older and seeks like any teenager to become more independent, new thoughts about insulin have started to crop up. Insulin is expensive, and while we have excellent insurance, that can always change in a heartbeat. But even if it does, the insulin must flow — she has no choice in the matter. And so I thought it would be instructional to take a look at how insulin is made on a commercial scale, in the context of a growing movement of biohackers who are looking to build a more distributed system of insulin production. Their goal is to make insulin affordable, and with a vested interest, I want to know if they’ve got any chance of making that goal a reality.

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