Canine Diabetes Wiki

The adrenal gland, producer of cortisol. Cortisol is produced by the outer portion, or cortex, shown here at right.

This is basically a process which happens to every person every day: the body prepares itself to go into "wake mode" and releases cortisol to ready itself for wake up.

In non-diabetics, it happens virtually unnoticed, as the properly working pancreas produces more insulin to handle the cortisol release. Persons without diabetes are unlikely to be checking their blood glucose values on a regular basis, so any temporary increases would not be measured.

As with almost everything else, not all diabetics are affected by dawn phenomenon, just as not all have post-prandial blood glucose spikes. If a person with diabetes believes he/she is having a control problem due to dawn phenomenon, the way to check is to take one's bg's at about 3AM for a few days and compare readings. A high or higher reading at about this time is likely due to dawn phenomenon and this can be managed by evening/night insulin increases.

Some current information regarding dogs and dawn phenomenon is that canines are said not to have an organized cortisol release. This means that they supposedly have no set pattern for them as humans do.

Personal experience with a canine message board dog says otherwise. The dog in question was suspected of having dawn phenomenon and was tested at 3AM for a few days, results being noted and compared. The 3AM readings all showed high/higher blood glucose values. He had received no food or insulin since dinner time (evening); breakfast (morning) food/insulin pattern results were as expected.

We have 3 studies confirming a cortisol pattern similar to humans, 3 which found no evidence of similarity and one which confirmed it in adult non-senior dogs only. This 2003 study [1] which refers to them found that some dogs do have a pattern similar to that of people and suggests the similarity be admitted but that the differences are more pronounced in humans.

It would seem from this that dogs can also experience dawn phenomenon as humans--some are troubled with it but others are not. More needs to be done for our pets regarding formal research into dawn phenomenon. I16


  1. J. KOLEVSKÁ, V. BRUNCLÍK, M. SVOBODA (2003). Circadian Rhythm of Cortisol Secretion in Dogs of Different Daily Activities. Clinic for Dogs and Cats, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Czech Republic.

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