Glucose is Higher in the Morning

Author: Judy Kohn, RN, BSN, CDE

Last Updated: Monday, February 13, 2006

Q: "I have been controlling my carb intake and have lost 40 lbs. Why do I have a surge in my blood glucose level between bedtime and my first morning reading, from 126 to 165? How can this happen after 8 hours of sleep and fasting?"

A: Since I originally posted this question in August 2001, I am not exaggerating when I say that this same question is asked literally every week.

This is a puzzling but common question that people ask, usually soon after they begin glucose monitoring. To paraphrase one of my patients: "Did I sleep walk during the night and eat cake? Where did that extra glucose come from?" I have had patients tell me they went to bed with a glucose level of 120, and woke up at 200.

First of all, congratulations on your successful weight loss. I'm sure you must feel that after all your efforts, why does your blood glucose still rise during the night when you haven't eaten?

First, a little review about how the body works. The cells in your body need glucose to function. Every time you eat, the level of glucose in your blood rises. Four to five hours after a meal, your blood glucose level returns to baseline. When you haven't eaten for a while and during the night when you are sleeping, your liver releases stored glucose to supply you with energy. In the early morning hours, (usually around 3-4 a.m.) your body produces growth hormone, which causes the liver to release this extra amount of glucose. I like to teach that your brain is saying "hey, he's going to wake up in a few hours--let's start cranking him up to give him some energy to start the day!" So this is actually a normal body rhythm, called the dawn phenomenon.

In the non-diabetic, the body automatically produces enough insulin to control the liver from releasing too much glucose. In fact, when the body senses a rise in blood glucose, it signals the liver to temporarily stop releasing glucose. Let's review the 3 roles of insulin:

1. Regulates the liver from releasing too much glucose (I like to say that insulin leans up against the door of the liver and only lets a little glucose out at a time).
2. Acts as a "doorman or key" to open the doors of the cells and allow glucose to enter the cells.
3. Acts as a storage promoter, to store extra glucose back into the liver, along with the muscles, while the excess is stored as fat.

In diabetes, either you don't make enough insulin, or the insulin you produce can't be used properly (called insulin resistance, which is estimated to be present in over 90% of all people with type 2 diabetes). Furthermore, most people with type 2 diabetes have an overproduction of glucose by the liver.

So what does this mean for you?

If you are diet or pill controlled, discuss this with your doctor and diabetes educator. Sometimes, the evening meal plan can be adjusted, or exercise after dinner might help. Depending on your weight goal, your physician may decide to wait to see if more weight loss makes a difference. Or, sometimes medication will be used at dinner time or bedtime to help control the bed time and early morning blood glucose.

Note: Although you clearly stated that your bedtime glucose is normal but the morning glucose is high, some people have written to me with concern that the pre-dinner glucose is normal and the morning is high. In this situation, it is impossible to determine the problem or the solution without further testing. For example, perhaps the pre-dinner glucose is normal, but you are overeating at dinner; as a consequence, the post-dinner glucose may be too high, as well as the bedtime glucose; going to bed with an elevated glucose might carry over through the night, resulting in a high morning glucose. So in this situation, the solution would be to either modify the dinner meal, or plan extra exercise after dinner.

If you are taking insulin, your physician will likely ask you to test before bed, test again around 3 a.m., and again when you wake up. This is to distinguish the dawn phenomenon from the somogyi effect. The somogyi effect is triggered by a low blood glucose during the night, which causes hormones to release which help to protect you from the hypoglycemia by causing the liver to release glucose. As you didn't mention insulin, I don't think this applies to you.

So, as you can see, careful monitoring, along with good records of your food intake and exercise habits, will help your healthcare team to determine what, if any, is the next course of action.

 

Related Questions

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Q: "How can I lower my morning readings? All other times are usually within an acceptable range but the morning fastings are a little high-up to 150. I have type 2 diabetes and I am not on any medication...."

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