A high blood sugar reading first thing in the morning can throw off your whole day — and signal a chronic problem. Despite their best efforts to control their blood sugar levels, some people simply wake up with elevated blood sugar. Starting your day this way is not just alarming — if it becomes a pattern, high A.M. readings can make it difficult to achieve your long-term diabetes management goals.

Whether you have type 1 diabetes or type 2, a morning blood sugar high can usually be traced to one of three causes. With a little detective work and the help of your diabetes care team, you can isolate the cause and take steps to correct it.

The Dawn Phenomenon

“The dawn phenomenon occurs during the night while you are asleep and the body releases stress hormones,” explained certified diabetes educator Hector Verastigui, RN, clinical research coordinator at the Texas Diabetes Institute in San Antonio. This phenomenon usually occurs between 3 a.m. and 8 a.m. and involves growth hormone, cortisol, and adrenaline, which trigger the production and release of glucose from your liver. The end result of this chemical cascade is an increase in blood sugar.

“These hormones are designed to get us up and moving in the morning,” said endocrinologist Renee Amori, MD, an assistant professor in the division of endocrinology at the Drexel University College of Medicine in Philadelphia. While everybody experiences these natural changes in hormone levels, in people with diabetes the body may not adjust appropriately. This can lead to higher-than-normal blood sugar at the start of the day.

The Somogyi Effect

High morning readings can also be caused by the Somogyi effect, a rebound response that occurs when the body overcompensates for a low blood sugar reaction in the middle of the night. "If you take blood-sugar-lowering medication [such as insulin] in the evening that may cause you to have a hypoglycemic reaction while you are asleep, your body will release these stress hormones that will cause you to have a high blood sugar in the morning,” explained Verastigui. If this is contributing to your high morning blood sugar, he said, you may experience symptoms related to hypoglycemia, including headache, excessive sweating while asleep and difficulty waking. “If your physician is increasing your evening diabetes medication to lower your morning blood sugar and your blood sugar keeps going up, you may be experiencing Somogyi," Verastigui said.

Waning Insulin

The third common cause of high morning blood sugar levels is waning amounts of insulin, which means your insulin levels are going down and no longer keeping your blood sugar in check. As a result, you wake up to an elevated reading.

Finding the Cause of Your Morning Blood Sugar High

Though the three most likely causes of high morning blood sugar can all be treated, first you have to know which one is the source of your condition. If you’re not sure, you might have to take the somewhat inconvenient step of waking up to check your blood sugar levels at 3 a.m. Here’s why:

  • Consistent blood sugar from bedtime until about 3 a.m. and then a rise suggests the dawn phenomenon.
  • Low blood sugar at 3 a.m. suggests the Somogyi effect.
  • Blood sugar that increases from bedtime to 3 a.m. and then is even higher when you wake is probably due to waning insulin.

Using a continuous glucose monitor enables you to get this information without having to wake up for it.

Treating High Morning Blood Sugar

A blood sugar high in the morning "can be tough to treat,” acknowledged Dr. Amori, but with the help of your medical team, you can try different approaches. Talk with your doctor about these strategies:

  • Adjust your pump. If you’re testing high regularly and you use an insulin pump, you might be able to program it to help manage your morning highs.
  • Check blood sugar before bed. Granted, many people have morning high blood sugar after an acceptable blood sugar at bedtime. Even so, “don’t go to bed with high blood sugar,” cautioned Amori.
  • Take basal insulin. Taking basal insulin at bedtime could help, but be sure to clear any changes in dosing with your physician before you try it.
  • Adjust medications. If in fact your high morning blood sugar is a rebound response to a low blood sugar level while you’re asleep, you might need to change the dose of any medication you take in the evening that could cause low blood sugars. For others, an evening dose of metformin could help control morning high blood sugar. Talk with your doctor about whether your medication schedule should be adjusted to treat A.M. highs.
  • Have a healthy pre-bed snack. For those experiencing the Somogyi effect, a healthy mixed snack (protein and carbohydrate) could help prevent your blood sugar roller coaster at night. Amori advises working with a registered dietitian if you’re not sure how to fit a pre-bed snack into your daily diet.
  • Increase physical activity. Being physically active during the day can help you manage blood sugar more effectively in general. If you are insulin-dependent or have a concern about low blood sugar, find out how to exercise safely before increasing your physical activity.

High morning blood sugar levels are a concern, especially if they happen regularly and seem to make it hard to meet your blood sugar goals. However, taking steps to address these morning highs can improve your overall diabetes management and stave off diabetes-related complications.