Why Blood Sugar Rises When You Wake Up: The Dawn Phenomenon Explained

Opening your eyes to high blood glucose levels can be disconcerting, especially when everything seemed under control the night before.

This increase, known as the dawn phenomenon, is a common condition in people with type 1 and type 2 diabetes, although it is rarely discussed.

According to the National Institutes of Health (NIH), more than half of people living with diabetes experience these morning sugar spikes.

A single episode may not be alarming; however, if it occurs frequently, it can become a serious risk to metabolic health.

What does the dawn phenomenon really mean?

The Cleveland Clinic describes this phenomenon as a morning hyperglycemia episode, which occurs between 3:00 and 8:00 a.m. Unlike other causes of high blood sugar, it is not preceded by a nighttime drop in blood sugar.

The dawn phenomenon is unique to people with diabetes, as their bodies are unable to efficiently regulate this natural increase in glucose at the beginning of the day.

Hormones in action: the causes behind increased glucose

During the early morning, the body prepares for the day by releasing hormones such as cortisol and growth hormone, according to the American Diabetes Association (ADA). These substances send signals to the liver to release more glucose to provide energy upon waking.

In a person without diabetes, insulin counteracts this effect. But in those living with the disease, the pancreas doesn’t produce enough insulin, or the body doesn’t respond adequately to it. As a result, blood sugar levels remain high at the beginning of the day.

It’s worth noting that other reasons for waking up with high blood glucose can include an inadequate dose of nighttime insulin, excessive carbohydrate consumption before bed, or an unbalanced diet.

Strategies for managing the dawn phenomenon

Although there is no universal formula, specialists recommend a personalized plan to keep glucose under control:

Adjust treatment: Talk to your doctor about changes in the dose or schedule of rapid-acting insulin.
Moderate exercise: Walking after dinner helps stabilize levels overnight; a short morning routine can also be helpful.
More balanced dinners: prioritize proteins and avoid simple sugars before bed.
Stress management: Techniques such as meditation or conscious breathing reduce the influence of adrenaline, another hormone that raises glucose levels.
Continuous monitoring: Using a CGM device can identify patterns and confirm the presence of the dawn phenomenon.

A manageable condition

Although it’s part of the body’s natural processes, the dawn phenomenon can represent an additional challenge in managing diabetes. Understanding its causes and implementing preventative measures can reduce its impact and improve daily quality of life.