||Drugs like glipizide (trade name
Glucotrol) and glyburide (trade name Micronase or Diabea) can sometimes be used to control
Although the exact mechanism of action is not known, it is believed that these drugs work
in several ways. Their strongest method of action is to stimulate the beta cells of the
pancreas to produce insulin. They also increase the sensitivity of other tissues to
insulin, either by causing insulin to bind to the insulin receptor more easily, or by
causing the cell to respond more strongly to the insulin, once it is bound to the
receptor. These drugs also have other effects on glucose metabolism. But the end result is
that blood glucose is lowered. Here's a refresher
on basic information about diabetes, insulin, and insulin receptors.
Since their main method of action is to stimulate the pancreas to produce insulin, the
pancreas must have functioning beta cells. These drugs will not work for a Type I
insulin-dependent diabetic where the pancreas does not produce insulin. Remember, in
Type I diabetes the pancreatic beta cells do not produce insulin and Type I diabetes is
always insulin dependent (IDDM). In Type II diabetes, there may be decreased
responsiveness of the body's cells to insulin, or, the beta cells may be functioning
improperly. Type II diabetes may be either insulin dependent (IDDM) or non-insulin
Dogs versus cats
Because the majority of dogs are Type I
insulin-dependent diabetics, oral hypoglycemic drugs are usually ineffective, and usually
not even tried as therapy. Some cats are Type I insulin-dependent diabetics and oral
hypoglycimic drugs will not work for these cats.
Many cats are Type II diabetics. For those that are non-insulin dependent, the
pancreas is producing insulin. It may be that not enough insulin is being produced,
or that the normal amount of insulin is being produced but the body's cells are not
responding to it properly.
There is no definite way to determine if a cat will respond to oral hypoglycemic drugs.
When the cat is diagnosed, the vet determines the cats overall health, the severity
of the diabetes, whether or not the cat has ketoacidosis or other diabetes complications
such as hind leg weakness (neuropathy), the cats ability to take pills, and the
owners desires (quick diabetes control, ability to give pills, etc.).
Diabetic cats that are generally healthy and not ketoacidotic are candidates for glipizide
therapy. That does not mean they should be started on glipizide, just that it is an
option. Cats who have severe symptoms or are ketoacidotic are not candidates for glipizide
therapy and are started on insulin therapy.
It is estimated that oral hypoglycemic drugs will work in about 1 of every 8 diabetic
cats. Some respond very well to the drugs, while others respond moderately, or not at all.
This probably depends on the amount of functioning beta cells that the cat has and
the amount of natural insulin that the pancreas is able to produce. In a cat that has a
large number of functioning cells, the oral drugs may be very effective. In a cat that has
a small number of functioning cells, the oral drugs may help, but it may not be sufficient
to control the hyperglycemia. In a cat with very few functioning beta cells, the oral
drugs may be ineffective at controlling hyperglycemia and insulin injections are required.
to glipizide include hypoglycemia, vomiting shortly after the pill is given, changes In
liver enzymes, and jaundice (icterus). Adverse reactions occur in less than 15
percent of cats who are given glipizide. Some possible adverse effects that have been
noted in humans include allergic skin reactions and bone marrow suppression. The
adverse reactions go away after the drug is no longer given, or sometimes when a lower
dose is given. When a cat is on glipizide, the vet should request lab tests to monitor
Treatment often starts by giving a pill of 2.5 mg twice a day with meals. The
cats health is examined weekly for the first month including physical exam, body
weight, urine glucose and ketone measurements, and bg tests. If there are no adverse
effects, the dose can be increased to 5.0 mg twice a day. Therapy continues as long as the
cat is stable. The dose can be adjusted depending on the bg values. If the bgs are not
controlled within 1 or 2 months of therapy, if the cats general health worsens, if
adverse reactions occur, if the cat becomes ketoacidotic, or if the owner is dissatisfied
with the slow progress, glipizide is discontinued and insulin therapy is begun.
Some cats become resistant to glipizide therapy and insulin is then needed.
For cats who have transient diabetes ("honeymooning"), glipizide may be
discontinued and the blood glucose remain normal. This is the same as transient diabetics
who receive insulin therapy.
is a cat whose
diabetes is successfully managed with glipizide and diet.
and Ginger are two guinea pigs
whose diabetes is managed with gliburide.
Ettinger and Feldman's Textbook of Veternary Internal Medicine,
Veterinary Drug Handbook, Second Ed. Plumb. 1995.
Updated October 2000
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