CGM Q&A Resource

Frequently asked questions about Continuous Glucose Monitoring (CGM) and Blood Glucose (BG)

Where should I apply my CGM?

• • Your CGM may be applied to the back of your arm or your abdomen. Please refer to manufacturer instructions for proper application and setup. If you need to troubleshoot your device, please refer to the links below.
  • Dexcom: FAQ + Troubleshoot Filter and Dexcom Care
  • Abbott: SetUp Support

Which CGM devices are compatible with Zero?

• • Zero works with any CGM that connects to Apple Health. You can connect to Apple Health through the Me tab, tapping the gear icon in the top right corner, then viewing "Connected Apps".

What can I do to maximize the life of my CGM sensor?

• • Your device is designed to remain attached for between 10-14 days (based on manufacturer). While CGM adhesion can sometimes be an issue, if you follow site preparation instructions you should have no issues. Particularly active users, or those engaging in water sports, may want to consider using breathable film (Tegaderm) or similar medical adhesive. Some manufacturers and third parties also provide decorative covers that will help adhere your device.

How accurate is continuous glucose monitoring? Should I consider calibrating my CGM?

• • Your CGM should not require calibration to be within reasonable accuracy limits. However, if your CGM device allows for calibration and you have an interest in calibrating your device then please adhere to directions provided by your CGM device manufacturer.

I've received alerts/alarms from my CGM, do I need to worry?

• • CGMs were originally intended for use in patient groups and include some alerts that may be less relevant for "healthy" individuals (see below). While there are notification settings you can edit to reduce alarms, you may not be able to remove 100% of alarms associated with your device. Please follow instructions and tutorials associated with your device from the manufacturer.

What is a "healthy" blood glucose level?

• • Research recognizes healthy blood glucose (BG) as between 70mg/dl to 140mg/dl. Healthy individuals should experience levels within that range the large majority of the time. If your levels are outside of this range that does not necessarily indicate that you are diabetic but may be something to discuss with your physician. This program is not designed to treat nor resolve diabetes.

What should my BG be when I wake up?

• • After an overnight fast (fasting for at least 12h) you can expect BG levels between 70mg/dl and 100mg/dl

How low is "too low" for my BG?

• • BG below 70mg/dl is defined as hypoglycemia. Generally, BG levels above 55mg/dl are not concerning in healthy individuals. If your levels are consistently below 55mg/dL or you are experiencing symptoms of hypoglycemia we recommend speaking to your physician.
  • It is normal to experience a variety of responses in your blood glucose, ranging from what we describe as monophasic to biphasic to triphasic responses. These will be covered in-depth in your CGM course.

How can I get the most of out my CGM and Zero?

• • We recommend logging your fasts and meals each day. While you are fasting you can log exercise, activity, and ketone levels within your Fasting Zones or the Me tab. While you are in your eating window be sure to log meals regularly so we can match them to any potential excursions outside of your glucose range.

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Have a question that isn't covered on this page? Feel free to contact Jeff Boyer at [e-mail]. You can expect to hear back within about 24 hours, although inquiries submitted on weekends may take until the next business day.