Why would someone with pre-diabetes have a normal blood sugar, 100 mg/dl [5.6 mmol/L] before bed yet wake up with a blood sugar of 132 mg/dl [7.3 mmol/L]? This is happening continually. Why would someone without diabetes have a spike in blood sugar overnight?

This is a very commonly asked question. In order to understand it, you need to know some background information. First, the brain requires a continual source of energy in the form of glucose. That means that the body needs to figure out a way to supply the brain with glucose around the clock, even when you are sleeping. This is usually done by regulating the amount of glucose that the liver puts out. The liver can take up glucose or amino acids (the building blocks for making proteins) and turn them into sugar. This sugar can then be stored in the form of glucose polymers called glycogen. This glycogen is then broken down when the body needs it. Usually, when insulin is present in sufficient amounts, glycogen breakdown is minimized and there is not a high level of glucose during the night and into the morning. However, with diabetes, insulin resistance or lack of insulin does not keep the glycogen breakdown in check and the glucose levels rise and give you the characteristic fasting hyperglycemia seen in patients with glucose intolerance or diabetes.

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