The Dawn Phenomenon

By Medically reviewed by Hello Doktor Medical Panel

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

What is the dawn phenomenon?

Your body changes continuously even when you are asleep. The dawn phenomenon is the result of those natural changes. Between 3 a.m. and 8 a.m., your body starts to increase the amounts of certain hormones that suppress insulin to drop blood sugar levels. They enter your system just as your bedtime insulin is wearing out and sugar levels rise.

Dawn phenomenon and type 2 diabetes

Your body undergoes a series of natural changes while you sleep: It generates higher amounts of particular hormones (growth hormone, glucagon, cortisol, and catecholamine [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.

If your blood sugar consistently low during 2 a.m. to 3 a.m, the Somogyi effect, also known as rebound hyperglycemia is likely to be blamed. The term refers to the pattern of high morning sugars preceded by an episode of low blood sugar, or hypoglycemia (usually with no symptoms, but night sweats can be a sign). Your blood sugar may drop too low in the middle of the night, so your body counters by releasing hormones to raise it. This could happen if you took too much insulin earlier or if you didn’t have enough of a bedtime snack. If it is normal or high during this period, the dawn phenomenon is more likely at fault.

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

Together with your blood glucose levels, the food you eat and your medicines can help your doctor to determine if your increase in blood glucose is from natural changes or the result of any other medical disorders. With 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.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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