AnnaMaria
Why Blood Sugar Spikes in the Morning — Even Without Eating
Many people with diabetes or prediabetes wake up to high fasting glucose levels despite not eating overnight. This common issue is often caused by the dawn phenomenon.
What Is the Dawn Phenomenon?
The dawn phenomenon is a natural rise in blood sugar that happens between 2 a.m. and 8 a.m. It affects both people with and without diabetes, but for those with insulin resistance, the rise can be more pronounced and harder to control.
Why It Happens
Early in the morning, your body prepares to wake up by releasing hormones:
-
Cortisol
-
Growth hormone
-
Epinephrine (adrenaline)
-
Glucagon
These hormones signal the liver to release stored glucose for energy. In people without diabetes, the pancreas produces enough insulin to stabilise levels. In those with diabetes, the insulin response is inadequate, so blood sugar remains high.
Signs of the Dawn Phenomenon
-
High fasting blood sugar in the morning
-
Normal or low blood sugar before bed
-
Morning fatigue, thirst, or brain fog
-
Dry mouth or headaches upon waking
If your glucose levels rise overnight despite a low-carb dinner, the dawn phenomenon is likely the cause.
How to Confirm It
Check your blood sugar:
-
Before bed
-
Around 3 a.m.
-
Upon waking
A rise between 3 a.m. and morning indicates the dawn phenomenon.
How to Control Morning Blood Sugar Spikes
-
Adjust evening meals: Limit heavy carbs, focus on protein, fibre, and healthy fats.
-
Late-night snack: A small protein-rich snack like Greek yogurt or boiled eggs may help.
-
Regular exercise: Improves insulin sensitivity; try a short walk after dinner.
-
Medication review: Work with your doctor to adjust insulin or oral diabetes medications.
-
Improve sleep quality: Poor sleep raises cortisol, which can worsen the dawn effect.
-
Limit late-night screen time: Blue light disrupts circadian rhythm and blood sugar regulation.
When to See a Doctor
Persistent high fasting glucose can increase the risk of heart disease, nerve damage, and vision loss. If morning spikes continue, your healthcare provider can adjust your diabetes management plan.
