If you’re waking up with high blood sugar—even after eating well the night before—you’re not alone. Morning highs are a common frustration for people with diabetes. Let’s break down why they happen and what you can do to get back in range.

Common Causes of High Morning Blood Sugar

🌅 1. Dawn Phenomenon

This is the most common reason. Between 3–6 a.m., your body naturally releases hormones (like cortisol and growth hormone) that prepare you to wake up. These hormones make your liver release extra glucose into your blood. If your insulin isn’t enough to match it, your blood sugar goes up.

• You go to bed with a normal blood sugar
• You don’t go low overnight
• Your glucose gradually rises around 3–6 a.m.

🌙 2. Somogyi Effect (Rebound Highs)

This happens when your blood sugar drops too low overnight, and your body “rebounds” by releasing hormones that push it too high.

Signs it’s the Somogyi effect:

• You wake up high after going low in the middle of the night
• You may feel sweaty, shaky, or have bad dreams
• CGM or a 2–3 a.m. check shows a low

🍔 3. Late-Night Eating, Unbalanced Dinners, or Snacking

If you eat a large meal or a carb-heavy snack right before bed—especially without enough insulin or medication—it may lead to elevated glucose in the morning. Here are some examples:

If dinner is high in fat: Think of a restaurant burger with some special sauce. this can slow your digestion of the carbohydrates in that meal, delaying how quickly the sugars from dinner get into the blood, and keeping them in the blood for a longer time before your body can get them out.

- The solution? Keep dinner moderate fat- no fried foods, no heavy creams and sauces.

If bedtime snacks have simple sugars: simple sugars, like fructose, lactose, glucose, and sucrose can all spike your blood sugar very quickly, and drop it quickly, too. But if you're going to bed, you won't use the sugar from that spike, and it won't help keep your glucose steady through the night.

- The solution? Avoid fruit, yogurt and milk at bedtime snacks. Make sure the snack is higher fiber and protein instead. Like a few whole wheat crackers and some cheese or peanut butter. Save the fruit and milk for a daytime snack.

If you eat the meal less than 2 hours before bed: while you're awake, your brain, muscles, heart, and all other body parts are using just a little more energy. you are not giving your body enough time to process the meal and use the energy.

- The solution? Aim to eat dinner 3 or more hours before you plan to sleep. If you can't change dinner time or bedtime, change your dinner balance: more protein and vegetables and less carbs with dinner will help control glucose through the night.

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💉 4. Too Little Long-Acting Insulin

If you’re using basal insulin, a dose that’s too low may not last through the night, letting glucose rise as you sleep.

How to Troubleshoot High Morning Glucose

1. Check your glucose around 2–3 a.m.
   • If it’s low: You may be having a rebound (Somogyi)
   • If it’s rising gradually: It may be dawn phenomenon
   • If it’s high all night: It could be food, missed meds, or not enough insulin
2. Look at your evening habits:
   • What time do you eat dinner or snacks?
   • Did you take your meds or insulin at the right time?
   • Did you drink alcohol before bed?
   • Did you have physical activity (or skip it) in the evening?
3. Talk to your care team:
   • You might need to adjust your insulin timing or dose
   • You may benefit from a small bedtime snack with protein and fat if lows are causing rebounds
   • CGM data can help pinpoint the pattern

Takeaways

Morning highs can be managed once you know the cause. Use your CGM (or check manually) at 2–3 a.m. to help uncover the pattern.

With the right adjustments, you can wake up in range and feel more in control. Always talk to your care team to double check your suspicions before taking action.