GlucoBalance consolidates and displays information stored in Apple Health.
Data can be loaded into Apple Health by a variety of methods / applications.
Glucose: CGM systems, glucose meters, manual data entry
Carbs: Dietary / food management apps, manual data entry
Insulin: Insulin pumps, manual data entry
Steps: iPhones, Apple Watch, Fitbit, etc.
Activity: iPhones, Apple Watch, Fitbit, etc.
The "New" tab allows you to manually enter blood glucose, carbs and insulin. But you do not need to ever enter data manually to receive benefits from the App. If you use a CGM system (e.g. Dexcom, FreeStyle, Medtronic) and have those systems write their data to Apple Health it will automatically read through to GlucoBalance for display and reporting.
When you install the app just grant Glucobalance access to all the Heath data as requested.