It exists as an example, so you can build one too.
Naterade is built on top of LoopKit. LoopKit is a set of tools to speed up development of your own app. It provides data storage, retrieval, and calcluation, as well as boilerplate view controllers. Most of all, it is agnostic to treatment decisions and input sources.
Can I run Naterade?
I would prefer that you didn't, because:
Your Diabetes My Vary
Your physiology, habits, and risk-tolerance are not the same as mine.