There are two forms of diabetes in dogs and cats: diabetes insipidus and diabetes mellitus.  Diabetes insipidus is a very rare disorder that results in failure to regulate body water content.  The more common type of diabetes is diabetes mellitus.  This disease is seen on a fairly regular basis, usually in dogs and cats 5 years of age or older.  Simply put, diabetes mellitus is a failure of the pancreas to regulate blood sugar.

Diabetes mellitus is a disease of the pancreas.  This is a small but vital organ that is located near the stomach.  It has two significant populations of cells.  One group of cells produces the enzymes necessary for proper digestion.  The other group, called beta-cells, produces the hormone called insulin.  In diabetes, the beta cells are not producing enough insulin to control the blood sugar, and it gets too high.

The Types of Diabetes

  1. Type I, or Insulin Dependent Diabetes Mellitus, results from total or near-complete destruction of the beta-cells. This is the only type of diabetes known in dogs. As the name implies, dogs and cats with this type of diabetes require insulin injections to stabilize blood sugar.
  2.  Type II, or Non-Insulin Dependent Diabetes Mellitus, is different because some insulin-producing cells remain.  However, the amount produced is insufficient, or there is a delayed response in secreting it, or the tissues of the cat’s body are relatively resistant to it.  Usually these cats will need insulin to get the glucose (sugar) under control, but sometimes with weight loss and a diet change the insulin injections can be discontinued.  People with this form of diabetes may be treated with an oral drug that stimulates the remaining functional cells to produce or release insulin in an adequate amount to normalize blood sugar.  Occasionally this is effective in cats, but because Type II diabetes does not occur in dogs, oral medications are not appropriate for treating diabetic dogs.