Why are Cushing's Dogs (and Stressed out People) Especially Susceptible to Diabetes?
The hallmark cause of Cushing’s disease is elevated cortisol levels. Cortisol is the key hormone that the body produces in response to a “fight or flight” stimulus. It causes a cascade of physiological effects, including suppression of the immune system, suppression of digestive and reproductive systems, breaking down bones, and, most important for present purposes, increases blood glucose levels. Increased blood glucose levels result from cortisol causing the release of stored glucose, the conversion of non-carbohydrates into glucose and blunting the effects of insulin. The additional glucose provides the body with the additional energy to mount a defense or flee a dangerous situation and then recover quickly following such an event. After the danger passes, cortisol levels return to normal and glucose levels follow suit. A typical fight or flight situation lasts only a matter of minutes or seconds. The body is well-suited to handle elevated cortisol over such a short period. However, in a Cushing’s dog, cortisol levels remain elevated for months and years. In turn, glucose (often called “blood sugar”) levels remain elevated.
Elevated blood sugar levels trigger the pancreas to produce more insulin because the body requires insulin in order to store or convert glucose into energy. Often the pancreas is unable to produce enough insulin to store or use all the sugar in the blood. This is a form of diabetes or pre-diabetes. In the short term, high blood sugar levels can lead to frequent urination, thirst, and fatigue, among other signs. In the long term, chronically high blood sugar levels can cause, among other effects, damage to eyes, kidneys and blood vessels, skin conditions, slow healing of wounds (a condition made worse by immunosuppressive effects of cortisol), and nerve damage.
An additional effect of cortisol that exacerbates the insulin problem is that elevated cortisol suppresses the effectiveness of insulin. This contributes to keeping blood glucose levels high.
What Can I Do To Prevent My Cushing’s Dog From Becoming IR or Diabetic?
The best way to prevent Cushing’s-related diabetes is to control your pet’s cortisol levels. Your veterinarian may prescribe medications, lignans and melatonin or another treatment to control cortisol levels in your dog.
In addition, diet and exercise are critically important in controlling blood sugar levels. Your veterinarian can calculate your dog’s ideal weight, and diet and exercise can be used to achieve that weight. Beyond just limiting the number of calories, the make up of the diet is also important. In general, diets that are high in fiber have been shown to lower blood sugar levels, and sugars and starches should be avoided to the extent practical. (This is why all of our products have been formulated so as not to contain any excipients or non-essential ingredients that would add starches or sugars.) Even some feeds that are marketed as being specially formulated for diabetic dogs may be too low in fiber and too high in starch or sugar for your dog, so consult with your veterinarian or a veterinary dietician about the right diet for your dog.
Is It the Same for Humans?
Yes, except worse. In addition to the environmental stressors that animals must contend with, humans also have to cope with a whole host of other stressors that arise from living in our modern world. These stresses may come from work, deadlines, examinations, family problems and a myriad of other sources. Each stressor will produce an elevated cortisol response that will recede only after the stress passes. If stress persists for a long period of time, then the same physiological effects as with our non-human animal friends can result. What is more, when cortisol levels are elevated as a result of stress (as opposed to as a result of Cushing’s syndrome
or injection of corticosteroids), then the sympathetic nervous system will also respond with its own cascade of physiological effects.