Doc: The dawn phenomenon in diabetes control

Keith Roach
To Your Health

Dear Dr. Roach: I hope you can shed some light on an issue that I have not seen you address: the dawn phenomenon. I am having trouble controlling my diabetes. I am 67 years old, and my mother was a “brittle” Type 2 diabetic who ultimately needed insulin twice a day. I have been on glipizide (10 mg) for three months now; before that, I was on 5 mg for about nine months.

I tried metformin for a short time, but it did not agree with me (cramps and diarrhea). I am overweight but working on it. I will admit that I love carbs, eat out often and I am known as a good Italian cook, hence, pasta and more carbs. My morning readings usually are 170 to 200. My bedtime readings are 130 to 150. I take my glipizide with my evening meal. Two hours after breakfast, my readings are in the normal range. My A1c is 6.9.

My husband is critically ill. He is significantly older than me, with COPD, congestive heart failure and lung cancer.

Can the added stress of caretaking affect blood sugars?


Dear B.P.: I am sorry to hear about your husband. Indeed, stress of any kind (and being a caregiver to a very ill loved one usually is extremely stressful) can make diabetes control worse. The stress itself can increase hormones (including cortisol and epinephrine), which act against insulin. Caregivers also routinely get poor sleep, which compounds the problem.

As far as the high sugars in the morning go, it could be due to the dawn phenomenon. This is a response to the surge in hormones that work against insulin (in this case, especially glucagon) that happens in the morning. Insulin resistance is higher at this time, so blood sugars tend to be high, as well.

However, there are other causes. One is the Somogyi effect, which is what happens after the blood sugar gets too low at night. The body responds by increasing those same anti-insulin hormones — cortisol, glucagon, epinephrine and growth hormone — to counteract the low blood sugar, resulting in a high blood sugar in the morning.

The way to tell whether high blood sugars in the morning are due to dawn phenomenon or Somogyi effect is to check the blood sugar early in the morning (around 3 a.m.), or to use a continuous glucose monitor.

Fortunately, your A1c level of 6.9 percent is in the range of acceptable for a 67-year-old. Even so, too many processed carbohydrates, like most pasta and white bread, is not the healthiest choice. I would recommend making some small changes by eating fewer starches and more vegetables and legumes.

Glipizide works by stimulating the pancreas to make more insulin. Most people on that drug alone eventually will need additional or different therapies.

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