What Is the Dawn Phenomenon?
The dawn phenomenon is a well-characterized problem that is common in people with and without diabetes. People without diabetes commonly need more insulin in the early hours of the morning to keep their blood glucose levels from rising. This need for more insulin is thought to be due to the natural circadian (biologic cycle of the body) elevations in anti-insulin hormones such as the growth hormone. If you do not have diabetes, the pancreas merely secretes a little more insulin during this time period, which is normally between the hours of 3 a.m. and 7 a.m. However, if your pancreas does not secrete enough insulin because you have diabetes, your glucose level will go up during this time unless you compensate for it. If no extra insulin is provided, the glucose will rise and be high when you wake up. As a person approaches middle age, the dawn phenomenon often declines or disappears entirely. The dawn phenomenon may vary from day to day, making controlling the glucose levels very difficult.
How Do You Manage It?
In order to combat the problem, many teens and adults with type 1 may require a higher basal rate in the predawn hours to counteract the natural increase in growth hormone production. If you have a continuous glucose monitor, you can determine exactly at what time in the early morning your blood sugar starts increasing. People using insulin pumps can take this information and adjust their basal rate appropriately to counteract the issue. Pumps provide temporary basal rates that can be increased or decreased in 1% to 10% increments for 1 to 72 hours as needed for illness, exercise, or other situations like the dawn phenomenon. Having an increased basal rate during the time of the dawn phenomenon is normally very effective at preventing the rise in glucose during those early morning hours. If you are on multiple daily injections and taking a long acting basal insulin, it is very difficult to target and control the dawn phenomenon.
How Do You Know If You Have It?
Testing for the dawn phenomenon is typically done overnight. Have an early dinner and make sure your post meal glucose value is between 120 and 180 at bedtime, with a horizontal trend arrow if you’re on a CGM. This makes it much easier to test your basal dose of insulin. If your glucose values go up overnight to more than 30 mg/dl from your bedtime value, the basal dose my need to be adjusted upward. If your glucose values stay flat until around 3am and then rise, the dawn phenomenon may be present.
It should be noted that not everyone experiences the dawn phenomenon, and on the flip side, in some cases the dawn phenomenon is so strong, no basal insulin at any dose can control it. This is when an insulin pump is truly needed.
The bottom line is that the dawn phenomenon is very common and can be easily treated with insulin pumps that can be programed to increase the basal rate during the early morning hours. If you are on multiple daily injections, the timing of the basal insulin may be important to counteract the issue.