The dawn phenomenon sometimes called the dawn effect, is the term given to an early morning spike in the fasting blood sugar in an individual with diabetes. Typically occurring between 2 and 8 AM, it can be frustrating for those who are making every effort to control their blood sugar. Fortunately, the dawn phenomenon can be effectively managed.
Everyone—those with or without diabetes—experiences a rise in blood sugar in the early morning. “There is a surge in growth hormone secretion in the early morning and this appears to be the hormone that may be the most responsible for the dawn phenomenon, at least in people with type 1 diabetes,” says Robert Courgi, MD, a hospitalist and endocrinologist at Southside Hospital in Bay Shore, New York. “The dawn phenomenon is apparently not only responsible for a rise in fasting glucose, but it can also account for an exaggerated rise in post-breakfast blood glucose.”
Growth hormone, as well as hormones like cortisol, are “get-up hormones that work to get us started on our day,” explains Yan Yan Sally Xie, MD, an endocrinologist at Long Island Jewish Medical Center in New Hyde Park, New York and North Shore University Hospital in Manhasset, New York. “But all these hormones cause glucose levels to rise.”
In a person who doesn’t have diabetes, there is sufficient insulin to cope with the blood glucose, or sugar, when it rises, Dr. Courgi says. “But in someone with diabetes, there’s just not enough insulin to control the sugar,” he adds. The pancreas isn’t able to produce insulin as needed, so the blood glucose rises.
“We know the dawn phenomenon is common and that blood sugar will vary with each individual,” says OnTrack Diabetes Editorial Advisor Amy Hess Fischl, MS, RDN, LDN, BC-ADM, CDE, who is also a diabetes educator and program coordinator for the Department of Endocrinology at the University of Chicago. “But if your blood sugar is regularly elevated in the morning, you are at an increased risk of long-term complications.” High blood sugars can cause your hemoglobin A1C to be higher than recommended, she says. You should strive for an A1C to be under 7%, according to the American Diabetes Association, or under 6.5%, according to the American Association of Clinical Endocrinologists.
It’s important for healthcare providers to educate the individual about what the dawn phenomenon is and to make sure that the high morning blood sugars are actually caused by the dawn phenomenon and not by poorly-controlled diabetes. “High sugars are indicative of uncontrolled diabetes,” Dr. Courgi says. “You may need more medication to get that sugar under control.”
If you have type 2...
If you have type 2 diabetes, your blood sugar is high in the morning, and you are not currently taking medication for your diabetes, you can try to avoid the dawn phenomenon by making some lifestyle adjustments, Hess-Fischl says. These could include taking an evening walk or eliminating your bedtime snack. But the chances of these really having an effect is slim, she admits. More than likely, she says, you may need either a medication change or a medication addition.
Eating dinner earlier as well as exercising in the evening could help, Dr. Courgi explains. “But in my experience, these are not all that effective,” he adds. And if these lead to hypoglycemia, the consequences can be devastating.”
If you have type 1...
If you have type 1 diabetes and your blood sugar is high in the morning, “It comes down to making adjustments in the insulin dosage,” Hess-Fischl says. If you have an insulin pump, she recommends working with your diabetes care team. “Fine tweaks can be made that will help at the time the blood sugars are rising and if you are on insulin injections, changing the dose can help as well.”
Pay attention to the type of snack you are eating at night. It should contain some carbohydrates but also some protein. Don’t drink sugary beverages like soda, fruit punch, and sweet tea. Even a single serving can raise your blood sugar beyond what it should be.
Those with type 2 diabetes may be told to inject a long-acting insulin at bedtime rather than during the day in order to control the blood sugar, while those with type 1 may go on an insulin pump and adjust it often, Dr. Xie says.
If you are waking up with high blood sugars for several mornings straight, ask your healthcare provider if it makes sense to check your blood sugar in the middle of the night—say, around 2 or 3 am—for a few nights. She will then be able to calculate whether you actually have the dawn phenomenon or if there may be something else that’s throwing off your numbers.
And keep in mind that there are 20 or 30 different variables that can affect the blood sugar at any one time, Hess-Fischl says. “Your blood sugar is impacted by exercise, by how large of a meal you eat, and by the composition of that meal, among so many other things,” she explains. “There are a lot of pieces to investigate before deciding that you are affected by just the dawn phenomenon.”