Diabetes Mellitus ("sugar" diabetes) is a fairly common
disease seen in the cat. There are two types: Insulin Dependent (IDDM), comprising
about 50-70% of cats, and Non-Insulin Dependent (NIDDM), about 30-50% of cats.
While NIDDM is usually caused by obesity, and is reversible, IDDM can be caused
by a variety of factors, including pancreatic islet amyloidosis, obesity, infection,
concurrent illness, certain drugs (such as cortisone), pancreatitis, genetic predisposition,
and immune-mediated insulitus.
Pancreatitis, islet amyloidosis, and renal insufficiency
secondary to diabetes have recently been strongly implicated in association with
both forms of diabetes. Many cats have a transient diabetes, in which insulin
requirements wax and wane, or sometimes disappear completely.
Both types cause the cat to develop "hyperglycemia",
unusually high blood sugar levels. The classic signs of Diabetes are an obese
cat with excessive thirst (polydipsia), excessive urination (polyuria), and a
ravenous appetite combined with weight loss. Some cats may develop a plantigrade
posture, where the hocks touch the ground when they walk.
The additional signs
of loss of appetite, weakness, vomiting, dehydration, and occasionally a strong
odor of acetone on the breath which may indicate a dangerous state in a diabetic
called ketoacidosis. Diagnosis of ketoacidosis is usually made upon measuring
large amounts of ketones in the cats urine. This condition is fatal if not treated
Diabetes is fairly easy to diagnose based on blood and
urine sugar levels, but a full blood panel evaluation, including thyroid levels
and urine culture, should be done initially to rule out concurrent disease.
There is newer blood test called serum fructosamine.
This test can measure the degree of glycemic control over the preceding few weeks
of a diabetic's life once on treatment and it can also be used to differentiate
stress hyperglycemia from true diabetes in ill cats. Diabetic cats who are stable
on treatment can often have the serum fructosamine test done instead of a 12-24
hour blood glucose curve for monitoring purposes.
Therapy includes a high fiber, high complex carbohydrate
diet, to aid in glycemic control and aid in weight loss. The diet should have
moderate Protein content, and low fat content. Examples include Hill's Prescription
Diet W/D, Science Diet Maintenance Light, or Iams Less Active.
should be fed their regular food until their weight is normal, then fed a high
fiber diet. Multiple small meals are preferred over one or two large ones, and
"nibblers" should have constant access to food. Since chronic pancreatitis and
exocrine pancreatic insufficiency (EPI) have been associated with diabetes mellitus,
a high fiber diet will be beneficial for both of these disorders.
Over dosage of insulin, failure to eat, or strenuous
exercise can cause "hypoglycemia", or low blood sugar. Signs include weakness,
lethargy, head tilting, seizures, and possible death. Treatment for hypoglycemia
should be the immediate ingestion of food, and transport to your veterinarian.
If a cat is unable to eat, Karo syrup can be rubbed on the gums, or slowly dribbled
into the mouth if the cat can still swallow (do not put your fingers into the
cats mouth--they can be unaware of what is happening, and bite you). Occasionally,
metabolic changes in the cats itself can lead to a reduction or end for insulin
therapy completely, so close blood sugar monitoring is important.
Insulin comes in several different types, and there
are alternate oral medications called glipizide or glyburide that may be appropriate
for some individuals. Oral glycemic control is difficult, however, and is only
effective for a small percentage of cats.
There are several different types of injectable insulin,
from very short acting (Regular), intermediate (Lente), and very long acting (Ultralente).
The type most often used on cats today is a human recombinant type insulin (Humilin
Ultralente), a long acting insulin. However, some cats have a reduced ability
to absorb insulin, or develop insulin resistance (for a number of different reasons),
in which case many different types and protocols must be tried before finding
one that works.
Initial treatment for a diabetic animal requires 24-48
hours of hospitalization for glucose monitoring during initial insulin administration.
Then, weekly 12-24 hour "glucose curves" are required to evaluate patient response,
lasting 4-6 weeks. Periodic glucose levels need to be monitored, how often depending
on how well the patient is responding.
With proper veterinary care by owners,
timely evaluations by your vet, and good owner-veterinarian communication, many
diabetic cats can live relatively normal lives for several years.
Further information on Feline Diabetes may be found in the following:
1.Feldman, Edward C., Nelson, Richard W. "Canine and
Feline Endrocrinology and Reproduction, 2nd Edition". WB Saunders Company, 1996;
by Jennifer Reding CFA Health Committee, reviewed by Nancy O'Day, DVM