Dawn Phenomenon

The “dawn phenomenon” is a term used to describe an abnormal increase in blood glucose (typically 10 to 20 milligrams per deciliter) in the early morning hours—usually between 2 and 6 a.m. It’s most common in people with type 1 diabetes, though it is possible for people with type 2 diabetes to experience it. 

Dawn Phenomenon and Type 2 Diabetes

Your body undergoes a series of natural changes while you sleep: It starts to generate higher amounts of particular hormones (growth hormone, glucagon, cortisol, and catecholamines [epinephrine, norepinephrine, and dopamine]) that increase insulin resistance and prevent your body from lowering blood glucose naturally. Some researchers believe this surge in hormones is responsible for the increased blood glucose level.

High blood sugar in the morning may have other causes, however. Poor diabetes management can result in a higher-than normal glucose level. Insufficient insulin, incorrect medications dosages, or eating a high-carbohydrate snack at bedtime can also up your blood sugar while you sleep.

Dawn Phenomenon Treatment

In addition to logging your blood glucose numbers, your doctor may ask you to record what you’re eating, as well as when you’re taking medicine or giving yourself insulin injections. He may also ask that you wake up during the night, between 2 and 3 a.m. for several nights, to test your blood glucose. This will help him determine if your increase in blood glucose is from natural changes or the result of something else. 

Using this information, he may adjust your medicine or insulin dosages, switch you to a difference medicine, or discuss using an insulin pump so that your body is able to get extra insulin during the early-morning hours.