5 months with HAPP - DIY, Artificial Pancreas

What Christmas dinner and a xDrip outage look like in HAPP

I have now been using HAPP as a usable Open Loop artificial pancreas notification system for over 5 months. Reviewing my time with HAPP, in summary I have found...


  • Visualising my real-time data allows me to better understand my condition
  • Bolus wizard with access to my CGM blood glucose readings is very handy
  • Notification every 15 mins if Basal adjustment is needed and linking the system with android wear makes it very usable and unobstructive
  • Having the system relieves a significant amount of pressure and stress with my daily management of diabetes
  • I rarely have to treat my hypos
  • I rarely go above 9mmol/l
  • I have completely removed rebounds from taking too much insulin or over treating a hypo
  • I do not need a higher Basal while traveling with HAPP (as I originally thought)
  • I am capable of Android Development (trust me I'm the most surprised!)

While travelling around Europe seeing family for Christmas I discovered my almost compete dependence on HAPP and it's supporting systems when my beloved xDrip died. A little hacking later and I had it up and running again. But, for 48 hours I was completely lost the insight I had started to take for granted with HAPP and felt I had fallen into the diabetes dark ages having to blindly guess my treatments.
Using HAPP has significantly reduce the burden of my type 1 diabetes and I now depend on the system.

Little creative thinking to protect the hack


Lets look a little deeper

Let's look at a few xDrip stats for the last 30 days (today 31st Dec)...

  • In range 90%, high 7%, low, 1% (target 3-9mmol/l) *see update below
  • Mean BG of 6.4mmol/l
  • Predicted HbA1c of 5.7%

Personally I am amazed at the results. Note that this was also over Christmas renowned for over eating and while travelling. While my last pre HAPP HbA1c was a respectable 5.8% my CGM charts did not back this up with daily BG swinging between high and low values (hence why some say HbA1c does not necessarily reflect your true BG management). With HAPP I have found that my % in range is significantly better now compared to around 50% in the past.

This is not just a one good month, xDrip 90 days stats report 89%, 9%, 1% for in target, high and low.

Do I have hard evidence to show this is due to my usage of HAPP? No. This could be down to me taking more of an interest in my condition over the last few months, maybe just being lucky? I can say HAPP has allowed me to better understand, feel more in control and empowered to manage my diabetes.

Putting to one side the 100s of hours worth of learning and development to build the app, all I have done is spent £30 to build xDrip and installed an app on my phone.
No technical breakthroughs, no high cost investments in devices, no significant learning curve or re-education, just my mobile phone, cheap smart watch and a Tic Tac box.

Think about that for a moment.


The future of HAPP

I believe there is a benefit in a Open Loop notification app to allow diabetics to take some of the guess work out of managing their condition without the full jump into a automated Closed Loop with the full APS system. Therefore HAPP will remain as a system to log and help visualise \ share data and provide suggestions \ notifications for Boluses with the Bolus Wizard and Basal adjustments with the selected APS algorithm. This means HAPP will not have any code to remotely control a pump, but will provide the ability to share its suggested Bolus and Basal adjustments to other apps.

Over the next few months I will be focusing my attention on...

  • Implementing additional APS algorithms that the user can switch between
  • Provide an secure interface for other apps to interface with HAPP and receive Bolus and Basal suggestions (For example pump drivers that can then provide a closed loop system)
  • Integration with other systems to share Treatments and other data (NightScout, Tidepool)
I am very interested to hear any feedback regarding HAPP and anyone who is using the app, do feel free to get in contact.

Github code & apk: https://github.com/timomer/HAPP
gitter.im chat group: https://gitter.im/timomer/HAPP


*update 06-01-15*

I was thinking that my target range seemed a little large in xDip (target 3-9mmol/l), I remembered that this was adjusted to allow HAPP more freedom to adjust basal rates to fix high and lows without me getting CGM alarms unless I was going very high or low. My old target was 3.6-8mmol/l so my in target range of 90% is a little over positive. Adjusting this my in target drops to around 75% - still very positive. Just goes to show keeping good log of treatment data is important, slap my wrist.


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The contents of this site is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your Diabetes support team or other qualified health provider with any questions you may have regarding your medical condition.Sorry, have to say something like this!