Meet the Bigfoot Family and Their Homemade Closed Loop System

Yes, Bigfoot does exist in the diabetes community and as you may have heard, he lives with his family in New York.

Our friends at diaTribe recently published a comprehensive interview with the mysterious man who'd long been rumored to have secretly created a homemade artificial pancreas system: D-Dad and husband Bryan Mazlish. Now, Bryan's teamed up with two fellow diabetes dads and big names in the community -- Lane Desborough, former chief engineer at Medtronic, and Jeffrey Brewer, who led the JDRF for four years until last summer -- to found a new diabetes startup called Bigfoot Biomedical, aimed at advancing connected closed loop technology. Bryan serves as chief tech officer.

Today, we're thrilled to share, for the first time anywhere, the full inside story of how "Bigfoot" began his work many years ago -- before there even was a #WeAreNotWaiting call to action! Bryan's wife, Dr. Sarah Kimball, is a longtime type 1 who works as a pediatrician in New York focusing on children with diabetes. They have three beautiful kids, one of them being 9-year-old Sam who was diagnosed with T1D at five years old. Sarah shares her family's story, and how they were first to use a closed loop system in their own daily lives.

A Guest Post by Sarah Kimball

For the past two years, I have lived unlike others with type 1 diabetes (T1D). I have lived easier, largely relieved of the hour-by-hour burden of managing my blood sugar -- all thanks to a so-called artificial pancreas system that automates my insulin delivery.

I walk around Manhattan with the system. I raise my three kids with the system. I work as a pediatrician. I go on long car trips. I get colds. And all the while, my insulin pump uses information from my Dexcom continuous glucose monitor (CGM) to adjust my insulin, smoothing out my blood sugars day and night.

For two years I haven’t worried about lows. A1Cs in the 6’s come almost effortlessly. I sleep through the night worry-free. I no longer have to keep my blood sugar a little bit high while I drive or see a patient. ALL aspects of managing diabetes are simpler.

The system was developed by the one person in the world I would entrust with both my safety and that of my child: my husband, Bryan Mazlish.

You might also know him as Bigfoot.

I want to share my experience with the tremendous mental freedom that comes with lifting the daily burden and fears of diabetes. Our story is a glimpse into the future for everyone with T1D, because Bryan and his colleagues at Bigfoot Biomedical are working to bring this technology to market with the urgency and diligence that only those who live with T1D can muster.

Here is our family's story.

My Diagnosis (Plus My Son's)

I’m not new to diabetes: I was diagnosed at age 12 in the early 80’s when shots of regular and long-acting insulins were the only way to manage T1D. I later embraced insulin pumps and CGMs as they became available. I can quantify my life with T1D. Twenty thousand shots. One hundred thousand fingersticks. 2,500 insulin pump infusion sets and hundreds of Dexcom sensors. I’ve worked hard to control my diabetes, realizing that, by doing so, I could ensure the best health possible for as long as possible. Thirty years out, I have no complications.  

But keeping my A1C in the low 6’s came at a price: I spent a lot of time thinking about diabetes. I counted carbs carefully, adjusted insulin doses frequently, did corrections diligently, and tested a dozen times each day. It seemed a third of my time was spent managing diabetes.

When pregnant with each of my three children, I was even more vigilant: at night I woke every two hours to ensure that my blood sugar was in range. Having a newborn was a relief after being so vigilant during pregnancy.

My third child was only three months old when I diagnosed our 5-year-old son, Sam, with T1D in 2011.

Even though I’m a pediatrician and have had years of personal experience with T1D, managing it in my own child was challenging. I worried constantly about severe lows since I knew just how awful they feel and how dangerous they can be. I started Sam on a pump the day after his diagnosis so that we could more precisely manage his insulin dosing. He almost immediately went into the honeymoon phase and I was anxious to keep him there for as long as possible. That meant that any blood sugar over 180 felt stressful.

A D-Dad’s Mission

Bryan whose career was in quantitative finance, had always been supportive of my diabetes, but had never been much involved in my day-to-day management because I did it so capably.

As soon as Sam was diagnosed, though, Bryan dove right into learning everything he could about diabetes and becoming an expert. Very early on, he expressed dismay at the antiquity of the tools available to us. He thought it was incredible that diabetes technology could be so very far behind the cutting edge of what was possible in other domains such as quantitative finance, where automated algorithms shoulder much of the work.

Shortly after Sam’s diagnosis in 2011, Bryan figured out how to communicate with the Dexcom and transmit its real-time values to the cloud.  It was absolutely fantastic -- we could watch Sam’s blood sugar trends while he was at school, at camp, or on a sleepover (much as Nightscout now does for thousands of families, but that’s a story for another day). We felt more secure letting Sam do things without us since we could easily text or call whoever was with him to prevent and/or treat impending lows or highs.

Over the next couple of months, Bryan taught himself about insulin and carb absorption and applied his experience with stock-trading algorithms to create models to predict future blood sugar trends. He incorporated this predictive algorithm into our remote monitoring system. Now we no longer had to have a screen with Sam’s CGM-tracing open at all times. Instead, we could rely on the system to alert us via text when it looked like Sam’s blood sugar was going too high or too low.

A couple of weeks after Bryan finessed the remote monitoring, he approached me with a question: “If there was one thing that could be made easier in your diabetes management, what would that be?” It was early in the morning and I had woken up with a BG in the 40’s; I was groggily making a latte, grumbling about how much I hated waking up low. I immediately responded, “If I could just wake up with a perfect blood sugar every morning, life would be so much better.

I explained how a good morning blood sugar, besides feeling great, makes staying in range the rest of the day far easier. I could see the wheels of Bryan’s mind turning. He was still working full-time in finance, but his brain was already more than halfway into the diabetes space. He was constantly thinking about diabetes, so much so that our oldest daughter, Emma, once said, “Daddy might as well have diabetes since he thinks and talks about it so much!”

Bryan set to work on this new problem. After a few months, he announced that he had figured out how to “talk” to an insulin pump. Busy with three children, I’m afraid I gave him a half-hearted, “Great!” and then turned back to whatever I’d been doing. I’ve lived long enough with diabetes to hear many promises of cures and life-changing innovations; I curbed my enthusiasm to avoid disappointment. Also, my experience with innovations thus far had been that they made life more complicated and added new burden to diabetes management, either by necessitating more gear or by producing more numbers to crunch. I certainly didn’t need more complexity in my life.

But Bryan was on a roll. Once he figured out how to talk to the pump, he didn’t see why the pump couldn’t be programmed to react to his predictive algorithms much the way the JDRF-funded academic trials had shown was possible. He kept working away, diligently and carefully. Every night when he came home from work he spent hours learning about artificial pancreas trials, insulin absorption curves, and carb absorption profiles. We spent many a night discussing insulin-on-board calculations and my experiences managing diabetes. He spent hours coding mathematical models that incorporated our knowledge about insulin and carb absorption. He created simulations to see the effects of changes in algorithm design. When we were together, all we talked about was diabetes. Whenever I gave a correction dose or temp basal, Bryan would ask me about my rationale for doing it.

We had a longstanding tiff about whether I could manage diabetes better than a computer.  I was convinced that my intuition, based on years of experience with diabetes, would always outdo a computer. Bryan believed in me, but he also believed that I could outsource some of that thinking to a smart machine and that, ultimately, a machine could do it better. He reminded me that machines are never distracted, never need to sleep, and never feel stressed about doing the work they are programmed to do.

One day in early 2013, after a great deal of rigorous analysis and testing, Bryan asked me if I would test out a pump that his algorithms could control. He showed the system to me. It was very bulky. I balked. How and where was I going to wear all this stuff? Wasn’t wearing a Dex and a pump bad enough?

For love of my husband, I said I would try it.

A Family’s Homemade Closed Loop System

I remember that first day on the system well: I watched in amazement as the pump gave me extra insulin to cover my latte spike in the morning and took insulin away in the late afternoon, when I usually got a late low from morning exercise. My Dex graph was softly undulating, fully in range. The system usually brought my blood sugar safely into range within two hours after a meal. Not having to do dozens of micro-adjustments was extraordinary. It was an amazing feeling for my blood sugar to head back into range without any input from me. I was immediately and unequivocally sold: the system gave me brain space immediately by micromanaging my blood sugars during the day.

But the nighttime security it has given me has been even more amazing. As long as I calibrate my Dex before bedtime and have a working insulin infusion site, my blood sugar hovers around 100 almost every night. I have the incredible and previously unimaginable joy of waking up with a blood sugar at or around 100 nearly every single day. No waking up with extreme thirst and irritability; no waking up groggy with a low headache. When Bryan travels, I no longer run myself on the higher side of my range overnight for fear of having a nighttime low alone.  

During the first few weeks and months of using the system, I learned how it worked and how to coordinate my blood sugar management with it. It was a novel feeling to have something always working with me to help to keep me in range. But it also meant that I needed to learn how to supervise the system and make sure it had what it needed to take care of me: a well-calibrated CGM sensor and a working infusion set. After closely watching the system deal with both mundane and new situations, I learned to trust it.

Over time, I stopped worrying about hypoglycemia. I stopped fearing lows with a BG of 90. I stopped doing correction boluses. I stopped thinking about carb ratios and insulin sensitivities. I stopped doing extended boluses for high fat or high protein meals (the system manages these beautifully!).  I stopped alternating pump profiles. My glycemic variability decreased.

A great deal of the burden of T1D was taken off my shoulders, and the system took care of me. I finally had to concede to Bryan that the machine does do it better than I could.

Together, Bryan and I worked on minimizing the alarms so that I didn’t get alarm burnout. We also worked on making an intuitive, easy-to-use user interface, one that babysitters, grandparents, teachers, nurses, and even a 7-year-old boy could use without difficulty. Our goal was to put Sam on the system, too.

A few months later, we were ready. We were both completely confident in the safety and usability of the system. Sam was still honeymooning (almost a year post diagnosis) so we wondered if it would benefit him.

The answer: Yes.

Having Sam on the system was absolutely amazing and life-changing. I stopped being a helicopter parent and counting every blueberry, because I knew that the system could take care of a few extra carbs here or there. I felt confident going to sleep and knowing that the system wouldn’t let Sam drop low overnight (or would alert me if it couldn’t). I was willing to send him to a camp that did not have an on-site nurse because I knew the system would adjust his insulin delivery as needed, both for impending lows and highs. The system helped Sam to honeymoon for nearly two years. His most recent A1C, post-honeymoon, was 5.8% with 2% hypoglycemia. What is most amazing about that A1C is how little we worked for it. We did not lose sleep over it; we did not stress over it. The system not only kept Sam’s blood sugars in range, but it kept us all feeling SAFE.

Bryan doesn’t stop at anything less than perfection. He realized that the size of the system was a significant downer. For months he worked on the system’s physical form. He wanted to make it wearable and livable. He did. I can now even wear a cocktail dress. One of the components that he developed for us is now being used by over 100 people in JDRF-funded artificial pancreas trials.

After 28 years of thinking day and night about my blood sugar, the past two years have finally allowed me to divert some of that brain power to other things. I just let the system do the work.

The system isn’t perfect, mostly because insulin and its infusion aren’t perfect. I still have to tell the system about meals to give the insulin time to work. I still get occlusions from shoddy infusion sites. While the system hasn’t cured me of diabetes, it has relieved a huge part of the burden of T1D, most notably the constant 24/7 micromanagement of my blood sugar, the fear of hypoglycemia, and the sleeplessness that accompanies that fear. I hope that someday soon, all people with T1D can feel the airiness of handing that burden over to a system such as ours.

I’m excited and confident that the team at Bigfoot will make this hope a reality.


Thanks for sharing the great experience you've had so far on your do-it-yourself closed loop, Sarah. We absolutely can't wait to see how it all moves forward!

Also, Dear Readers: stay tuned for another story coming soon about another "do-it-yourself" AP system developed on the opposite side of the country, part of the ever-growing #WeAreNotWaiting community.

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Originally published at DiabetesMine


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