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. 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. Can the added stress of caretaking affect blood sugars? — B.P.

ANSWER: Indeed, stress of any kind can make diabetes control worse. The stress can increase hormones, which act against insulin.

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 that happens in the morning.

However, there are other causes. One is the Somogyi effect, which is what happens after the blood sugar gets too low at night. 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.