Normal level at bedtime (91), up 35 points in morning (145).

by Frances Rose
(Nashville, NC (USA))

QUESTION: Why is my Blood sugar 91 when I go to bed at night and 145 when I get up in morning? Nothing to eat or drink during night.

ANSWER: Hi Frances,

I understand your concern.

Your blood sugar at bedtime is completely normal (91 mg/dL). During the night, you are not eating or drinking anything.

In the morning, you find your blood glucose as high as 145 mg/dL.

Ok, there are 2 main explanations for this:

1. Morning hormones: they include cortisol, growth hormone, chatecholamines.
They get higher in early morning. They induce the production and secretion of sugar from liver with high blood glucose as consequence.

In non-diabetic people, this high blood sugar is associated with increased insulin production and secretion to lower it.

If cannot produce enough insulin, the result is having high morning blood sugar levels. This is called Dawn Phenomenon.

2. Somogyi effect: in early morning, blood sugar is very low as response to insulin.
Your body reacts by realeasing morning hormones to increase blood sugar.

When you measure early morning, you find your blood glucose raised.

Now, what I suggest to my patients is to measure their blood sugar levels in the first hours of morning (e.g. 2 to 3 a.m), and record the results.

If your blood sugar at this time is low, then, you get high blood sugar in the morning due to Somogyi effect.

This can be corrected by having a snack at bedtime.

If blood glucose is normal at 2 to 3 a.m, then, this is Dawn Phenomenon.

I'd suggest to measure HbA1C level to evaluate your blood sugar average within the last 3 months.

Hope this helps. Let me know if you have further queries.


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