Controlling the Dawn Phenomenon

by David Mendosa Patient Advocate

One of our most stubborn challenges is to control the dawn phenomenon. That's when our fasting blood glucose readings in the morning are higher than when we went to bed.

The dawn phenomenon is a normal physiological process where certain hormones in our body work to raise blood glucose levels before we wake up, as we wrote in The New Glucose Revolution: What Makes My Blood Glucose Go Up...And Down? Professor Jennie Brand-Miller of the University of Sydney, Kaye Foster-Powell, and I co-authored that book (Marlowe & Co., first edition 2003, second American edition 2006).

These so-called counter-regulatory hormones, including glucagon, epinephrine, growth hormone, and cortisol, work against the action of insulin. They stimulate glucose release from the liver and inhibit glucose utilization throughout the body. The result is an increase in blood glucose levels, ensuring a supply of fuel in anticipation of the wakening body’s needs.

If you take insulin injections, it could be that the effect of insulin you took is waning. Your blood glucose will rise if you didn’t take enough to keep your insulin level up through the night.

The dawn phenomenon varies from person to person and can even vary from time to time in each of us. That much was clear when our book came out.

But how to control it was a different story. A couple of years ago here I wrote about several efforts for “Taming the Dawn Phenomenon.” People have tried everything from eating a green apple at bedtime to high-maize grain to uncooked cornstarch.

None of these remedies that I have been able to try ever worked for me. I always thought that the most promising remedy was one that a correspondent named Renee suggested – vinegar capsules.

"I am still using vinegar tablets (usually 8) each night and have used vinegar when tabs are not handy," Renee just tells me. "I have never added food to that, however. I still do have success in reducing the morning reading as proven by the times when I do not use the vinegar tabs and the reading in the a.m. is usually 20 points higher. I am doing well overall with an A1C of 5.6 for some time now. I have been on Byetta for a year now and have lost 35 pounds."

This makes sense, because several studies in the professional literature clearly show that vinegar can reduce our blood glucose levels.

One of these studies, by Dr. Carol Johnston and two associates in the department of nutrition at Arizona State University in Mesa, Arizona, is particularly intriguing. They reported that “Vinegar Improves Insulin Sensitivity to a High-Carbohydrate Meal in Subjects With Insulin Resistance or Type 2 Diabetes” in a 2004 issue of the professional journal Diabetes Care.

Now, Dr. Johnston and an associate have zeroed in on using vinegar to control the dawn phenomenon. Their study, “Vinegar Ingestion at Bedtime Moderates Waking Glucose Concentrations in Adults With Well-Controlled Type 2 Diabetes, appears in the November 2007 issue of Diabetes Care.

They tracked four men and seven women who have type 2 diabetes and were not taking insulin. These people kept 24-hour diet records for three days and measured their fasting blood glucose at 7 a.m. for three consecutive days. They took either 2 tablespoons of apple cider vinegar or water at bedtime with 1 ounce of cheese (8 grams of protein, 1 gram of carbohydrate, and 1.5 grams of fat).

The result was that when they took the vinegar, they cut their fasting blood glucose by about 5 mg/dl (0.26 mmol/l). That was twice as much as what the placebo group did.

And when Dr. Johnston and her associate took a closer look at the data, they found that the vinegar treatment was particularly effective for those people who had a typical fasting blood glucose level of more than 130 mg/dl (7.2 mmol/l). Vinegar helped this group reduce their fasting blood glucose by 6 percent compared with a reduction of 0.7 percent in those people who had a typical fasting blood glucose of less than 130 mg/dl (7.2 mmol/l).

It might not have been just the vinegar that was at work, the authors concluded. Cheese might have a synergestic effect with it. Nobody knows yet, and taking it with the vinegar could be a good idea, especially since it makes the vinegar more palatable.

But “this is the first report describing a hypoglycemic effect of vinegar apart from mealtime,” they concluded. It is a big step forward in our continuing attempts to control the dawn phenomenon.

UPDATE January 9, 2008: Another strategy to control the dawn phenomenon may be to drink a little alcohol with dinner. A study reported in the December 2007 issue of Diabetes Care that the fasting plasma glucose of volunteers who drank 13 grams of alcohol in the three-month trial dropped 32.5 mg/dl compared with those in the control group.

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.