access garmin heartrate data in python to combine with CGM data

Hi, as a type 1 diabetic i wear a continuous glucose monitor (Dexcom 6) which records my blood sugar values every 5 minutes. I also wear a Garmin 735xt, which - among others - records my heart rate. I want to combine these two in a python script, to predict my blood sugars. Can somebody point out to me what to use to access the Garmin data and import it in Python?