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The first home-made artificial pancreas – in Croatia!
December 2, 2020 / Uncategorized

The first home-made artificial pancreas – in Croatia!

24 min read

 How do I write what an OpenAPS system is without being “too technical”?  Hard, but I’ll try.  To begin with, I will quote the OpenAPS documentation:

 “Any person choosing to use these tools is solely responsible for testing and implementing these tools independently or together as a system.”

 A prerequisite is the use of a pump that is compatible with OpenAPS and a CGM device that constantly monitors and stores glucose values.  Some of the possible combinations are Libre with NightRider or Dexcom G4 with xDrip or Parakeet and the new Dexcom G5.  All together with NightScout.










How do you regulate your diabetes or your children’s diabetes?  Do you collect information and experience it into actions?  If the sugar rises do you make corrections?  If it falls, do you reduce the basals and suspend the pump?  The OpenAPS system does the same, only automatically.

 OpenAPS consists of a “RIG”, a computer that collects data and performs calculations, RIG communicates and controls the pump via a radio stick (or board) and reads data from it (boluses, basals).  RIG also communicates with your phone or cloud via wifi to gather additional information and sends you a report on everything it does.


 Here is all the documentation you need to start learning about OpenAPS.  It’s not easy, but it pays off.  There is no logic in you having to wake up to correct sugar during the night when the computer can do it for you.

 When we say it’s a closed loop system, don’t think that’s the end of the diabetes story for you.  The system does not give boluses (fast-acting insulin for a meal), you have to do it yourself.  What it does – reduces peaks, calculates the basal cell count and insulin sensitivity.  It’s not a box you buy and works, it requires a lot of tuning, tracking logs, recharging batteries, basal corrections and technical knowledge, but it definitely pays off.

 OpenAPS in action

 Left Libre is without “home automation”, while the right is with OpenAPS

 To the left is a graph of a person on pens with three corrections of that same pen, to the right is Ema’s graph with OpenAPS’s automatic basalt adjustment on the pump, all after yesterday’s dinner: plenty of melted cheese, white bread, boiled potatoes and lettuce (fondue and raclette).  We didn’t even cover this short hypo with carbs the morning before.

 Security is one of the more important reasons I got into it.  All pump models on the market are officially approved, have passed rigorous tests, and are on sale within the EU.  The fact that a pump is used does not make it worse than the pump we received from the HZZO.  Before using it, we tested it offline for a long time, and after setting it, I monitor glucose 24/24, and not only through an alarm (the first night I was awake all the time).  I think I’m a lot safer like this than before, given that I have remote and complete control, both of the pumps and the glucose trend.

 I didn’t know what was going on before, and now in 4 days of use we had 4 minutes of glucose below 4 mmol / l with a flat trend, and 87% of the time from 4.3 – 9 mmol / l; which we could only dream of before.  1 dextrose correction in 4 days!  Things can always go wrong, you have to weigh which is less evil, pump (any) or foams, CGM or finger prick.  Hyper and hypoglycemia or good trends, but always doubt the technology.  There is no safe way.  I couldn’t wait that long, because when will the official pump with a loop come to Croatia?  And at what price??

 EdIntel Edison – “What will you make”?


 This is an Intel Edison with a battery, it is practically the whole computer on one module intended for making small so-called “Wearable devices”.  Edison must be a maximum of about 5 meters away from the pump, it has Linux with an OpenAPS application that controls the pump remotely.  Must have an internet connection or a direct connection to Dex.  It is acceptably small and can be bought at GalagoMarket for around € 65.  We also need a communication add-on called “Intel Edison explorer board” which costs $ 74us on the Enchanced devices webshop.

 In general, there is much less hypo; smaller amounts of carbohydrates eaten is the program itself able to cover and iron.  Not everything is perfect, there is a lot of running in at the beginning, mistakes, especially at the time when we started with OpenAPS, but we are slowly getting used to it.  2 nights there was no alarm, tonight only at 7 in the morning, and that’s what makes me happiest.

 This is what openAPS nights look like.  After 2 weeks, the computer that manages the basals § (autosense) calculated the insulin sensitivity itself and there are no more deviations.  At the top, the dice with numbers 0.75U, 0.15U show you how the computer only changes the basals depending on the readings of the Libre sensor.  Nights without alarm.  For dinner there was hot chocolate with whipped cream and chestnuts, which used to keep me awake at night.


 OpenAPS, Looping, closed loop and artificial pancreas are just some of the terms I use in this article, and they refer to the system that controls the pump so that based on the readings (glucose values) from the CGM (in my case Libre sensor), manages the pump’s temporary basals and thus prevents hypo or hyper.

 So, the prerequisite for using the OpenAPS system is that you have: CGM (Libre + Ambrosia or Dexcom), an insulin pump and in our case an Android mobile phone, and an Internet connection.  While the Loop system works with the iPhone.

 CGM – we use the Libre sensor, which houses the Ambrosia Nightrider – which sends glucose values ​​via bluetooth to the xDrip + app on an Android mobile phone.  To complicate your life a little more, we calibrate xDrip and Libre every now and then with blood and this information is sent to a Cloud application called Nightscout.

 Insulin pump – we use Medtronic 512, bought used, approx. 300 usd.

 RIG – is a computer that controls the insulin pump via radio connection, and receives glucose readings via the Internet / wifi from the cloud (Nightscout).  The RIG consists of an Intel Edisonmini computer that still has an “explorer board” (or Explorer block) on it for a radio connection to the pump.

 Mobile phone – Android with Bluetooth

 It is used to receive data from Ambrosia NightRider, which it forwards to the Nightscout cloud, and at the same time it is a mobile access point when RIG is not in the domain of known wifi.


























 There is also the option to send data directly from xDrip on your mobile to RIG, without using the internet, but I haven’t gotten to that part yet.

 You can follow all this on the Nightscout web portal or on the papertrail for logs.

 Note, do not do this if you are unsure, the responsibility for all consequences is solely on you.

 An example of how it all works

 At night, our basal is tuned to about 0.5 units per hour.  CGM reads values ​​every 5 minutes, our goal is to maintain glucose levels at 5.5 mmol / l.  If the value is higher, the “temp basals” on the pump are raised to a value that the OpenAPS algorithm calculates will return glucose to 5.5.  If the value goes below and the trend is falling, the “temp basal” is reduced or switched off completely – to avoid hypoglycemia.

Night “autopilot”

 Before you eat (approx. 60 min) there is a button / option on the mob, “meal soon“, which sets the target value of blood glucose to 4 mmol / l, raises the basal temp and thus when you start eating it irons the graph, so there are no more jumps.

 The procedure is the same before physical activity or training, you have the command “training soon” where the target value rises to 8 mmol / l, and the “temp basals” decrease.  We are making progress every step of the way and we are pleased with the progress, but I repeat once again, all the responsibility for my family is solely on me and my technical knowledge.  Likewise, neither I nor the portal can take responsibility for any problems that may arise from the use of this information.

 Find the continuation of this story in the article:

Ema and the artificial pancreas (part II)

Ivica Suran Read more posts by this author
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