CGM Alerts and Alarms: How to Set Them Up Smarter with Type 1 Diabetes

If you've been living with Type 1 Diabetes for any length of time, you know the sound. That buzz, beep, or vibration from your CGM that pulls you out of a meeting, wakes you up at 2am, or goes off mid-bite at dinner. CGM alerts are one of the most powerful tools we have — but if they're not set up thoughtfully, they can become background noise you start ignoring. And that's where things get risky.

Let's talk about how to approach your CGM alert settings in a way that actually works for your life — reducing the noise without losing the safety net.

Why CGM Alerts Matter (and Why They Can Work Against You)

Your continuous glucose monitor is designed to keep you informed in real time. High alerts, low alerts, urgent low alerts, rate-of-change arrows — it's an incredible amount of information that previous generations of people with T1D simply didn't have access to.

But here's the reality: when alerts go off too frequently, alarm fatigue sets in. Studies in diabetes technology have shown that people who experience constant CGM alerts are more likely to start silencing them, snoozing them, or outright ignoring them. That's not a personal failing — it's just human nature. Our brains are wired to tune out repeated stimuli.

The goal is to make your alerts meaningful. Every alarm should feel worth responding to.

Understanding the Different Types of CGM Alerts

Before adjusting anything, it helps to understand what each alert type is actually doing for you.

Urgent Low Alert

This is the non-negotiable one. Most CGMs have a fixed urgent low threshold (often around 55 mg/dL or 3.1 mmol/L) that cannot be turned off. This alert exists because a severe low can happen fast and requires immediate action. Keep this one loud and obvious.

Low Glucose Alert

This is your customisable early warning system. Setting it too high (say, 80 mg/dL / 4.4 mmol/L) means it fires constantly, especially after exercise or during periods of tight control. Setting it too low means you might not have enough time to respond comfortably. Work with your diabetes care team to find a threshold that gives you a useful heads-up without constant interruption.

High Glucose Alert

High alerts are incredibly useful for catching post-meal spikes or missed boluses — but they're also one of the biggest sources of alert fatigue. If your high alert is set at 140 mg/dL (7.8 mmol/L), it may trigger after almost every meal. Consider whether your current threshold is realistic for your day-to-day management goals.

Rate of Change Alerts

These alerts notify you when your glucose is rising or falling rapidly — often shown as double arrows on your CGM screen. They can be incredibly valuable (especially for catching a fast drop during exercise) but can also over-alert if your glucose naturally moves quickly after meals. Not all CGM systems let you customise these, but knowing what they mean helps you respond appropriately.

Practical Tips for Setting Up Smarter CGM Alerts

1. Start With Your Real-Life Patterns

Before changing any settings, spend a week reviewing your CGM data. When are alerts firing most? Are you getting repeated low alerts overnight? Constant high alerts after breakfast? Identifying patterns first helps you make targeted adjustments rather than guessing.

This is where an app like iSpike can be genuinely helpful — logging your meals alongside your glucose trends gives you a clearer picture of what's driving those alerts.

2. Use Different Profiles for Different Times of Day

Some CGM systems (and connected apps) allow you to set different alert schedules. Your daytime alert needs are different from your overnight ones. At night, you might want a lower threshold for your low alert so it wakes you with more time to act. During the day, you might tolerate a slightly higher threshold because you're awake and checking regularly anyway.

3. Don't Silence Alerts — Adjust Them

There's a big difference between turning off an alert because it's annoying and adjusting the threshold because it's not set appropriately for your management. The first leaves you unprotected. The second is smart personalisation. If you find yourself constantly dismissing an alert, that's a signal to revisit the setting — ideally with input from your diabetes care team.

4. Check Your Alert Volume and Delivery Method

This sounds basic, but it matters. Is your CGM alert loud enough to wake you at night? Is it set to vibrate only during a work meeting when you really need to notice it? Many people set up their alerts once and never revisit the delivery settings. Make sure the alert can actually reach you in the situations where you need it most.

5. Revisit Your Settings After Life Changes

Starting a new exercise routine? Changed your insulin regimen? Shifted work schedules? Your glucose patterns will shift too, which means your alert thresholds might need updating. A good habit is to review your CGM alert settings every few months — or any time your routine changes significantly.

A Note on Sharing Alerts with People You Trust

Many CGM platforms offer follower apps that allow a family member, partner, or close friend to receive your alerts on their phone. This can be an incredible safety feature, especially overnight or during activities where you're less able to respond quickly.

If you use a follower setup, have an honest conversation with your follower about what the alerts mean and when they should act versus simply checking in with you. The goal is support, not anxiety — for either of you.

Finding the Balance

There's no single perfect alert configuration. What works brilliantly for one person with T1D might drive another person up the wall. The sweet spot is a setup that keeps you genuinely safe, gives you actionable information, and doesn't leave you so overwhelmed by noise that you start tuning it out.

Take the time to review, adjust, and personalise. Your CGM is one of the most powerful tools in your T1D toolkit — and getting your alerts right is how you make sure it's actually working for you, not against you.

---

This article is for informational purposes only and does not replace advice from your diabetes care team.