The Future of OpenAPS with Dana Lewis


The artificial pancreas system, or artificial pancreas system (APS), is arguably the most life-changing technology developed for people with type 1 diabetes in recent years. You may be familiar with the Medtronic and other commercial systems available in the U.S. and in Europe—but there is another option out there for those in the diabetes community who are ready to make change for themselves. The DIY movement is taking the diabetes community by storm, starting with the Open Artificial Pancreas System (OpenAPS) that allows everyday type 1-ers to use their insulin pumps and continuous glucose monitors (CGMs) in order to close the loop.

Beyond Type 1 recently sat down with Dana Lewis, who shared with us how the OpenAPS system has changed her life. Her diabetes journey is fascinating, and Dana gave us a behind-the-scenes look at the technology that can seem almost too good to be true.

From “No Pump”…

When she was first diagnosed with type 1 at age 14, Dana didn’t even want to wear a pump.

“I remember on day one, my pediatric endo came in and said, ‘Things are going to be great! You’re going to go to camp, you’re going to get a pump,’” she told us, “and I was like, “Whoa whoa whoa. I’ll deal with the diabetes, but if I wear a pump, everybody’s going to look at me and see diabetes, and not see me.”

What changed her mind? Dana’s love of sleep.

“I didn’t like waking up at 7am, having to eat, having to inject, then going back to sleep. The benefits of pumping and being able to sleep were worth people looking at me and knowing that I had diabetes.”

Accepting her type 1 diagnosis led to Dana’s passionate involvement in the diabetes community ever since: “I was a National Youth Advocate for ADA, so I did a lot of speaking and a lot of traveling even during my teen years with diabetes, which allowed me to learn about things like CGM and talk about research a lot earlier on than I would have otherwise.”

As she got older, a CGM alarm that didn’t always wake her up during the night while living alone after college (combined with a fondness for sleeping through the night!) was the main catalyst that led Dana to investigate a DIY setup.

“I developed a plan with my mom where she would text me in the morning, every day, to make sure I was awake. That’s really what ultimately drove me to get into the DIY space because I was just so frustrated with not having an alarm I could change on the device. I stumbled across John Costik on Twitter—he had figured out how to get data off the CGM—that’s what enabled me (and my now-husband, Scott Leibrand) to first build a louder alarm system, then add an algorithm to it to predict the future, which I used in an “open loop” for about a year. Then we met Ben West, who figured out how to communicate with the Medtronic pumps, and the lightbulb went off: Oh, if you put all these things together, we could actually close the loop.

“And so we did that in December 2014,” she said, “It was immediately as life-changing as having the louder alarm. That’s when we decided to call it OpenAPS and make it widely available to anybody who wanted to do it. We didn’t want anybody to feel alone if they wanted to build a system and do it in the safest way possible.”

…to “No Bolus”

Dana continued, “When we first designed the system, it was a hybrid closed-loop where you still bolused, you still carb-counted and entered them and the system kind of picked up in the background and you still got way better outcomes. I’ve been on a DIY closed loop now for about three and a half years, and we have learned a lot and improved the algorithm a lot. Between algorithm improvements and having switched to a faster insulin (Fiasp) I have not bolused for the majority of meals for the last 11 months. I do a simple meal announcement, which is, I’m eating a meal, small, medium, or large, and the system ramps up my dosing and I get the same, if not better, outcomes as I was getting when I was manually bolusing.”

Dana loves that data can identify “what is the quantifiable impact of entering a meal versus not? Of bolusing ahead of time versus not? You could try your very, very, VERY hardest and still not get the A1c that you wanted; technology can help us change this.”

She went on, “A closed-loop system is even a step further: instead of having to choose what to do, I’d say 95 percent of my diabetes tasks have been removed on a daily basis. I have to do a couple things. I’ll pick up my “rig,” what we call the artificial pancreas, and clip it on my pocket, I’ll change my pump sites, I’ll change my CGM sensor once a week. I do maybe three or four diabetes-related things a day. The cognitive burden reduction is so big.”

We really wanted to know: Is there anything Dana misses about the old way of doing diabetes things?

“The answer is…no. Everything was just worse! I was either high or I was low or I didn’t know and ignorance was bliss, but I just felt bad all the time during the day. It was a hassle.”

How DIY Works

It turns out that you don’t have to be a computer scientist in order to access this data and close the loop yourself. If you can follow directions, you’re all set!

Dana explained: “If you can use Facebook or email, which basically means, “operate a web browser,” and read instructions, that’s all you need! We actually find that people who come from non-technical backgrounds do really well, once they kind of get over that self-fear of, I’m not an engineer! I can’t do this! I’m not technical!, and they allow themselves to try. Everybody who tries succeeds. The people who don’t succeed are the ones who don’t try.”

“Like when you go from multiple daily injection (MDI) to pump,” Dana said, “It’s absolutely a transition. It’s not going be perfect on day one, there’s going to be steps of getting comfortable and tweaking it, and then diabetes is diabetes. You still have to change your pump site, you still have to calibrate your CGM [editor’s note: unless you’re using the Dexcom G6, of course!]. Going in with the right expectations really impacts success.”

Life-changing Outcomes

Some people in the OpenAPS community are taking it one step further and not even announcing when they are eating. Dana gave an example of one teenager who eats 225g of carbs per day and does not announce that to his APS. He is spending about 75 percent of time in range and 25 percent out of range. Can you guess what his most recent A1c was?

We’ll give you a hint: it was in line with what Dana’s modeling predicted it would be in a session she gave at the ADA Scientific Meetings this year!

“He doesn’t bolus, he doesn’t announce his meals, driving his parents nuts,” Dana laughed, “And, truly, this person has a 6.2 A1c. Even knowing what I know, that just blew me away. What I love about this is, having the tools and the data to be able to understand the behavior tradeoffs.”

Being able to share the experience of getting much-needed—and, in the diabetes community, highly coveted—sleep is another one of Dana’s favorite results of creating and using the OpenAPS.

“That’s why I did this,” she said, “It’s really rewarding for me when I hear parents who say, ‘I haven’t slept through the night since my kid was diagnosed, and with OpenAPS, for the first time I slept through the night.’ Hearing stories like that really drives me because I get how impactful sleep is. There’s other reasons why people choose to do this, for sure—there’s better outcomes, the quality of life, the treatment reduction related to diabetes, I think is as important as the traditional things like A1c and time in range.”

Sharing the success

Allowing everyone to freely access and customize the code to use the DIY system was a critical part of its inception, and it remains so today.

“Developing the community and bringing people together as part of this open source community was really important to me,” said Dana, “I knew that having the community come together in some online channels would be really instrumental in helping each other. That, to me is the magic of it: the collaboration and the community element. You get the smartest people in the room, regardless of their role, and social media allows us to do it in a way that wasn’t possible even five years earlier.

“That communication of: here’s what we’re doing, here’s what’s working, here’s where we’re struggling—that really allows the snowball effect of the community to be so powerful. To me, it’s really important not just to do this thing, but to share it so that other people can use it. I want this information to be in the right place, at the right time, for the people who need it.”

Learn about Looping – The DIY Artificial Pancreas.

WRITTEN BY Katie Doyle, POSTED 08/08/18, UPDATED 10/28/22

Katie Doyle is a writer and videographer who chronicles her travels and diabetes (mis)adventures from wherever she happens to be, and she’s active in the community as an IDF Young Leader in Diabetes. She’s written about dropping her meter off of a chairlift in the Alps, wearing her pump while teaching swim lessons on Cape Cod and the many road trips and fishing expeditions in between—she’s up for anything and will tell you the story about it later. Check out for more.