To determine if you have diabetes or pre-diabetes, you must consult with your primary care physician and have a blood test or A1C test performed. If you are interested in learning more about your risk of diabetes, you can read more from the ADA here and the CDC here.
Continuous Glucose Monitors (CGM) devices are a part of the January program. In the U.S. they are FDA cleared or approved for use for the management of diabetes and by persons with diabetes. If you don't know if you have diabetes or are at risk of diabetes, you can also complete the signup process to have a medical professional determine if you are eligible to wear a CGM.