If your fasting glucose is higher than your bedtime reading, you're experiencing the dawn phenomenon — and you're not alone. About half of people with diabetes do.
What causes it
Between 3 AM and 8 AM your body releases cortisol, glucagon and growth hormone to wake you up. In a healthy pancreas, insulin counters this surge. With diabetes, that counter is weak — so glucose rises.
How to tell it apart from the Somogyi effect
Both cause morning highs, but for opposite reasons:
- **Dawn phenomenon**: steady rise from 3 AM onward
- **Somogyi (rebound)**: a low overnight that triggers a counter-regulatory spike
Test glucose at 3 AM for three nights. If you're low, it's Somogyi. If you're steadily climbing, it's dawn.
6 strategies that work
- **Walk for 10 minutes after dinner**. Cuts morning glucose 20–30 mg/dL on average.
- **Eat dinner earlier**. Finishing by 7 PM gives your pancreas a longer fast.
- **Add protein at bedtime**. A small snack (cheese + almonds) can blunt the morning rise.
- **Cut carbs at dinner**, not breakfast. A high-carb dinner sets up a worse morning.
- **Improve sleep quality**. Poor sleep raises cortisol the next morning.
- **Talk to your doctor about metformin timing**. Taking it at bedtime helps many people.
When to call your doctor
Consistent fasting readings over 130 mg/dL despite lifestyle changes warrant a medication review.