The Diabetic Pet

What is Diabetes Mellitus?thCALZ9NXJ

To understand the problems involved in Diabetes Mellitus, it is necessary to understand something about the normal body’s metabolism.  The cells of the body require a sugar known as glucose for food. However, cells can’t absorb and utilize glucose without insulin.  Insulin is a hormone produced in the pancreas.  Think of insulin as a key that unlocks the door to separate cells from the sugars in our bloodstream.

Glucose comes from the diet.  When an animal goes without food, the body must break down fat, stored starches, and protein to supply calories for the hungry cells. Proteins and starches may be converted into glucose. Fat, however, requires different processing that can lead to the production of ketones rather than glucose.

Ketones are another type of fuel that the body can use in a pinch; but, the detection of ketones indicates that something wrong is happening in the patient’s metabolism.  Ketones may therefore be detected in the urine of starving animals because of massive fat mobilization is required for ketone formation.  Ketones can be detected in diabetic ketoacidosis, a severe complication of unregulated diabetes.  So, it is helpful to monitor a diabetic patient’s urine for ketones,  periodically.  During periods of extreme fat burning (such as in starvation), ketones are a byproduct.

When there isn’t enough insulin in a diabetic animal

  • The cells cannot receive glucose from the blood because there is no insulin to permit it.
  • The body is unable to detect the glucose in the blood and is fooled into thinking it is starving.
  • Protein, starch, and fat break-down occur as they do in starvation.
  • Yet all along there has been plenty of glucose in the blood.  In fact, by now, there is a large excess of glucose as all resources have been mobilized.  Still, without insulin, this bounty of fuel cannot get to the tissues that need it.
  • The normal kidney is able to prevent glucose loss in urine.  In a diabetic animal, there is so much glucose in the blood that the kidney is overwhelmed and glucose spills into the urine and is lost.
  • Glucose is able to draw water with it into the urine.  This leads to excess urine production and excess thirst to keep up with fluid loss.

Clinical signs of Diabetes Mellitus

  • Excessive eating
  • Excessive drinking
  • Excessive urination
  • Weight loss

It is usually fairly clear from the history and tests showing dramatic glucose elevations in the blood (and usually glucose in the urine, too) that diabetes mellitus is the diagnosis.  Some pets are able to substantially raise their blood sugars from stress (such as might occur when a sensitive, sick and anxious patient goes to the vet’s office).  This could create misleading test results.  If there is any question about the diagnosis, a test called a fructosamine level may be requested.  This test reflects an average blood glucose level over the past several weeks so if this is also elevated, a one-time elevated glucose can be distinguished from the persistent elevations of true diabetes mellitus.  The fructosamine test is also sometimes used in monitoring therapy for diabetes mellitus.

Type I and Type II

Diabetes Mellitus is a classical disease in humans and most of us have heard some of the terms used to describe it.  In humans, diabetes is broken down into two forms:  Type I and Type II.  In short, Type I Mellitus is where the pancreas produces no insulin at all, but in Type II the pancreas produces some insulin but not enough.  Virtually all dogs have Type I diabetes and must be treated with insulin.  Most diabetic cats have Type II diabetes.   For cats, there is potential for diabetes to resolve if the pancreas improves its insulin-secreting ability.  Insulin injections are needed to treat most diabetic cats.  Good glucose control and proper diet can resolve the diabetes in some lucky cats, but virtually never in dogs.