Can a user connect to any version of Apple watch?

You may connect any Apple Watch model to the InsideTracker app. In order to share data from your Apple Watch to InsideTracker, you must have the Health app installed on your phone. (Of note, the Health app is different from the Activity App). If your iPhone is running on iOS 8 or higher, the Health app is automatically installed on your iPhone. However, a series 3 Apple Watch or above is required to track sleep data by wearing your Apple Watch to sleep. If you’d like to track your sleep duration but have a series 2 or below, you can still manually enter your time asleep in the Health app.