The Dawn Phenomenon: A Diabetes Puzzle Solved

by David Mendosa Patient Advocate

The dawn phenomenon is one of the most disturbing challenges for those of us who have diabetes. Many of us wonder about the puzzle of why our blood sugar level spontaneously rises during the last hours of sleep each night.

This has also mystified our doctors and medical researchers, so much that they have published at least 187 articles in the professional literature during the past three decades since the first study of the subject appeared. But four new studies by European researchers just published in American professional journals have shown a bright light that clarifies the major questions we have had about the dawn phenomenon. We now know who gets it, how bad it is, how much it impacts our A1C levels, and how to prevent it.

Whether you have type 1 or type 2 diabetes you are likely to have the dawn phenomenon. However, dawn levels among people who don't have diabetes rise only slightly, if at all, "because they secrete insulin to prevent it," according Francesca Porcellati, MD, and her associates at Italy's University of Perugia. Their study, "Thirty Years of Research on the Dawn Phenomenon: Lessons to Optimize Blood Glucose Control in Diabetes," appears in the December 2013 issue of Diabetes Care, a professional journal of the American Diabetes Association. The full-text of this study is free online.

Whether you are managing your diabetes with diet alone, an insulin sensitizer alone (like metformin or Avandia or Actos), or an insulin secretagogue (like the sulfonylureas or Prandin or Starlix or Januvia) combined with an insulin sensitizer also doesn't make a difference. This is one result of research led by Louis Monnier, M.D., of France's University Montpellier and his associates. Dr. Monnier is one of the world's most respected diabetes researcher, and his study, "Magnitude of the Dawn Phenomenon and Its Impact on the Overall Glucose Exposure in Type 2 Diabetes:Is this of concern?" appears in the same December 2013 issue of Diabetes Care as the Porcellati study. While only the abstract of this study is available online, my friend and associate at HealthCentral, Dr. Bill Quick, kindly shared his full-text copy with me.

How old you are also doesn't make a difference. Dr. Monnier and his associates studied age in relation to the dawn phenomenon and reported their finding a year ago in "Frequency and severity of the dawn phenomenon in type 2 diabetes: relationship to age."

For most of us how much our blood sugar level rises during the last hours of the night varies tremendously from day to day. This is another important finding that Dr. Monnier and his associate reported in their new study.

But how much does our level have to rise to justify calling it the dawn phenomenon? Some earlier studies chose an increase of 10 mg/dl as the threshold. But Dr. Monnier's group selected an increase of 20 mg/dl as the threshold for several reasons, including their observation that this is closer to the average amount of the rise among people with type 2 diabetes.

This typical increase in our blood sugar levels from the low near the middle of the night to our pre-breakfast level naturally impacts our overall diabetes control. But until now, we haven't known how much difference the dawn phenomenon makes.

We do now. On average among the 248 people whom Dr. Monnier and his associates studied for their most recent report, A1C levels increased 0.39 percent because of the dawn phenomenon. For example, someone who has the dawn phenomenon and an A1C level of 7.0 would have had an A1C level of 6.61 if he or she had been able to manage it.

Let's put this in context. Some of the diabetes drugs we take don't make a bigger difference.

So controlling the dawn phenomenon is clearly worth our attention. The biggest question is how. Comments on three earlier articles that I have written here about the dawn phenomenon show that those of us who have diabetes have attempted many different strategies. The one that seems to work, however, is not one mentioned in any of the more than 100 online comments to these articles.

What works, according to the new study by Dr. Porcellati and her associates, is taking basal insulin at bedtime. It "abolishes the dawn phenomenon [and] is an effective treatment." It mimics way that insulin works among people who don't have diabetes. The Porcellati study cites their poster presentation at the ADA's June 2013 convention in Chicago that Diabetes reprinted in that professional journal's annual supplement.

These basal insulins include Lantus and Levemir. They give us a very long-acting insulin boost -- as much as 24 hours -- and they aren't tricky to handle like the short-acting bolus insulins that need to be matched in amount and time with the food we eat and the activity we get.

I have one caveat. A conflict of interest can subconsciously bias the thinking of anyone, and each of the four co-authors of the Porcellati study in Diabetes Care report receiving honoraria or travel grants from Sanofi or serving on one of that company's advisory panels. Sanofi makes Lantus, which controls 80 percent of the basal insulin market.

Still, using one of the basal insulins to manage the dawn phenomenon makes sense. You don't need to believe or disbelieve this recommendation. You can check it out for yourself.

David Mendosa
Meet Our Writer
David Mendosa

David Mendosa was a journalist who learned in 1994 that he had type 2 diabetes, which he wrote about exclusively. He died in May 2017 after a short illness unrelated to diabetes. He wrote thousands of diabetes articles, two books about it, created one of the first diabetes websites, and published a monthly newsletter, “Diabetes Update.” His very low-carbohydrate diet, A1C level of 5.3, and BMI of 19.8 kept his diabetes in remission without any drugs until his death.