Setting appropriate & realistic alerts
for your Continuous Glucose Monitor (CGM)
To get the most out of Continuous Glucose Monitoring (CGM), you want your system to work with you — not against you. The key is to set CGM alerts that will help you be proactive with your diabetes management while minimizing life disruptions.
REMEMBER: the information provided is not intended to replace your physician's instructions. Always consult your healthcare team before making any changes to your CGM alerts settings.
Your first week
For the first 3-7 days using CGM, simply watch what is happening without taking action. This is important to prevent overcorrecting while allowing you to learn from your normal trends. It is not unusual to be out of the target range more than half of the time when starting CGM. Over time, these fluctuations can be fine-tuned.1
Low alert settings2
- To help prevent hypoglycemia, as demonstrated below, set the low alert just above the lowest value of your target glucose range:
High alert settings
- Balance the value of high alerts with the nuisance they can cause and avoid ‘alarm fatigue’.
- Make adjustments to the high alert as you begin getting more comfortable with your CGM.
Adjustment of high-alert setting over time
Your first month: minimize alerts & alarms:
Consider the following:
- Set the high alert at a level well above “desirable”.
- Set the low alert at the lowest point of your acceptable glucose range.
- Set the alert ‘snooze’ time for at least 2 hours (high) or 1 hour (low).
✔Always re-check your blood glucose with a fingerstick test 15 minutes after treating a low.
It may take longer for your CGM to ‘catch up.’
- Turn off the rate-of-change alerts (unless fall rate warning is necessary to help avoid hypoglycemia).
- Choose reminders that will produce the fewest possible disturbances.
- Calibrate on a regular schedule, especially before bedtime.
- If using a CGM receiver, be proactive in keeping it charged.
Getting more comfortable with your CGM? Consider adding rate-of-change alerts.
- Consider setting at 0.17 mmol/L/min to alert you when glucose is falling too rapidly.
- If glucose is falling at this rate for 15-20 minutes, you may need to consume rapid-acting carbohydrate to prevent subsequent hypoglycemia.
- Consider setting at 0.17 mmol/L/min to alert you when glucose is rising too rapidly.
- A rapid rise rate could indicate problems such as2:
- Infusion set problem
- Forgetting to bolus
- Spoiled/expired insulin
- A stress response
- A missed dose of insulin (or other diabetes medication)
- A medical issue such as an adverse reaction to a medication, an intense allergic reaction, or a developing illness or infection
Be sure to seek help from your healthcare team to prevent prolonged hyperglycemia or ketoacidosis.
Don’t base treatment decisions solely on results from your CGM — always confirm a CGM reading with a fingerstick test first.
When first starting with CGM, many people find seeing the variability in blood glucose to be overwhelming. But it’s important not to over-react, and to see CGM as an opportunity to learn how blood glucose behaves in response to food, exercise, stress, etc. Once you get used to seeing all the data, the alerts can guide you to get on top of excursions sooner and ultimately help prevent dramatic highs and lows.
1. Hirsh et al. “Clinical Application of Emerging Sensor Technologies in Diabetes Management: Consensus Guidelines for Continuous Glucose Monitoring (CGM).” Diabetes Technology & Therapeutics; 2008 Aug;10(4):232-44.
2. Scheiner, Gary. “Practical CGM: A guide to Improving Outcomes through Continuous Glucose Monitoring.” American Diabetes Association; 2015.