Yoon Hang Kim MD  |  www.directintegrativecare.com

Why Blood Sugar May Be High in the Morning

Understanding the dawn phenomenon, overnight lows, and what to do about morning glucose spikes.

Waking up to a high blood sugar reading can be frustrating and confusing. For many people, morning highs happen for a reason that is common, predictable, and manageable.

Why morning blood sugar rises

One of the most common causes is the dawn phenomenon. In the early morning hours, your body naturally releases hormones that signal the liver to release glucose into the bloodstream. This is normal, but in some people, blood sugar rises too much before breakfast.

Other possible causes include:

• Not enough overnight medication or insulin.
• The timing of diabetes medication not matching your body’s needs.
• A late-night snack, especially one high in carbohydrates.
• Poor sleep, stress, or illness.
• Less commonly, a rebound high after an overnight low.

Dawn phenomenon vs. overnight low

Not all morning highs are the same. If blood sugar drops too low during the night, the body may respond by releasing extra sugar, which can cause a high reading in the morning.

That is why it helps to look at the full overnight pattern instead of just the morning number. If you use a continuous glucose monitor, the overnight trend can be very helpful. If you check with finger sticks, a bedtime check and an early-morning check can give useful clues.

What you can do

If morning highs happen often, try these simple steps:

• Check blood sugar before bed and again when you wake up.
• If possible, check once around 3 a.m. for a few nights to see what your glucose is doing overnight.
• Avoid large carb-heavy snacks late at night.
• Keep dinner balanced with protein, fiber, and healthy fat.
• Talk with your healthcare provider about whether your medication dose or timing should be adjusted.
• Review sleep, stress, and recent illness, since these can also raise blood sugar.

When to get help

You should talk with your clinician if:

• Morning highs happen regularly.
• Your blood sugar is very high.
• You wake up sweaty, shaky, or with nightmares, which may suggest overnight lows.
• You use insulin and are unsure how to adjust safely.
• Your blood sugar pattern is changing for no clear reason.

A simple example

For example, if your blood sugar is normal at bedtime but much higher when you wake up, the cause may be the dawn phenomenon. If your blood sugar is low at 3 a.m. and high by morning, that may suggest rebound from an overnight low.

Bottom line

A high morning blood sugar reading is common and often manageable. The key is figuring out the pattern behind it so you and your healthcare team can choose the right fix.

directintegrativecare.com  •  Yoon Hang Kim, MD, MPH