From Veterinary Practice News, 2008
Feline Diabetes: New Ways of Looking at an Old Enemy
Tight Regulation Gets Job Done
By Elizabeth Hodgkins, DVM, Esq.
Veterinarians today see many diabetic cats. In fact, evidence exists that the number of diabetic cats is growing; at least, more of them are presented to practitioners for treatment than ever before.
Feline diabetes has been a very discouraging disease to manage. Patients are often brittle and unpredictable in their response to insulin and other measures to control hyperglycemia. For most of us, these cats have been unsatisfying to treat, with decline and death all but a certainty.
Human adult onset (Type 2) diabetes is also on the rise, according to most sources of human health statistics. Physicians attribute this to poor-quality, high-carbohydrate diets, inadequate exercise and other lifestyle factors that conspire to develop this life-threatening condition.
The only good news in this epidemic of human diabetes is the strides being made in helping diabetics to better manage and live with the disease. These include:
These three measures, implemented faithfully by the diabetic human, give the patient longevity and quality of life. Even Type 1, or juvenile, diabetes is amenable to this type of management. Often, human diabetics can escape dependence on insulin by following proper diet and regular blood-glucose monitoring at home.
Fortunately for our feline diabetes patients, veterinarians can and should follow the lead of our physician colleagues.
There is no reason for our profession to ignore the benefits diabetic patients can experience with a carefully crafted management plan of the same type that humans use every day. While veterinarians likely will never have the benefit of recombinant feline insulin, proper diet and regular home testing offer unprecedented opportunity for restoring diabetic cats to a level of health never before available.
The three facets of my protocol for “tight regulation” (TR) are proper diet, blood-glucose readings and insulin.
A study done by a group of which I was a part at Heska Corp. in the late 1990s showed that high levels of processed carbohydrates contribute to the poor blood-glucose control that is so common in feline diabetics. Subsequent studies by Debra Greco and Jacqui Rand verified this study.
It should be noted that virtually all dry cat foods contain high levels of highly processed carbohydrates from grains or high glycemic-index vegetables such as potatoes. Changing the diet of the diabetic cat to low-carbohydrate canned or homemade food brings immediate, significant improvement of hyperglycemia.
In fact, the diabetic patient on a particular dose of insulin while on dry cat food must reduce this dose at the same time the diet is changed to low-carbohydrate because the exogenous insulin requirement will drop dramatically.
Real-Time BG Monitoring
Veterinarians typically instruct owners of diabetic cats to give a set dose of insulin once or twice daily without real-time knowledge of the patient’s blood-glucose level at dosing. This is shooting blind. While veterinarians once had little choice but to manage diabetics this way, today the practice of shooting a potent drug like insulin without real-time blood-glucose information is not only unnecessary but unnecessarily dangerous.
I have managed hundreds of feline diabetics in the past decade. During that time I have used most of the human glucometers as well as one marketed specifically for animals. I have found all human meters to correlate well with my in-clinic and reference laboratory blood-glucose levels and have found no significant difference between human meters and the veterinary brands.
Because pet owners are using the same meter consistently to do their serial blood-glucose determinations, the trends that these determinations provide are valid for making insulin-dosing decisions, even if the individual numbers differ in some small way when compared with other, less convenient testing methods.
Glucometers are extremely affordable and can be mastered by more than 90 percent of clients.
Home testing allows pet owners to determine exactly how their cats are responding to any starting dose of insulin and provides an enormous amount of information to the veterinarian for how to adjust that dose.
In essence, home testing of BG not only mimics the human method of managing diabetes, it mimics the manner in which the pancreas naturally controls the blood-glucose level to prevent hyperglycemia and the tissue damage that results from prolonged hyperglycemia.
A healthy pancreas senses the glucose level in blood and continuously secretes tiny amounts of insulin into the systemic circulation in response to upward fluctuations of blood glucose due to food intake or stress, for example.
Insulin helps the glucose enter the body’s cells, and a very tight homeostatic balance is maintained.
In diabetics, little or no insulin is available from the pancreas, and the glucose level in the blood elevates and remains elevated.
When physicians and veterinarians use insulin to restore some of that homeostasis, they understandably lack the minute-by-minute “sense” of glucose level that is a feature of the healthy pancreas, so they must use much cruder and less frequent measurements to make the dosing decisions that the pancreas would make in the healthy animal.
Physicians long ago realized that effective treatment depended on making BG measurements as frequently as possible and matching the administered dose of exogenous insulin to the actual BG level with each insulin shot. So the human medical profession had patients test at home, with administration of insulin if those levels indicated hyperglycemia and the need for insulin.
In contrast, veterinary practitioners continue to estimate each patient’s needed insulin with only a few BG data points to make this long-term decision. Insulin is then administered once or twice daily in blind fashion by the pet owner.
Every few weeks, the diabetic cat may have a new BG curve performed at the clinic or, alternatively, a fructosamine test. From these tests, the daily dose of insulin may be recalculated, and the owner repeats the process of shooting blind for several weeks.
Both the one-day glucose curve and fructosamine test are unnecessarily crude in light of the new opportunities afforded by home BG testing used in humans.
BG curves performed in the veterinary facility are, of course, subject to the white-coat effect on the feline patient, with artifactual elevations in the BG all too likely. Even if this effect is not dramatic, the curve is at best just a snapshot of only a few hours in the patient’s life.
Fructosamine is similarly flawed as an assessment tool in the previously diagnosed diabetic. It is an indirect rolling average of BG measurement in the preceding few weeks. Short-term upward and downward trends that may be occurring in the animal under the blind bolus administration of insulin are obscured.
The diabetic patient managed in this manner often experiences clinically important episodes of diabetic ketoacidosis or hypoglycemia because of the inaccuracy of these methods of deter- mining insulin dosing.
Home testing of BG is an easy and practical way to avoid this kind of crude approximation and its clinical consequences. The perception that clients are unwilling or unable to perform home testing and logging is incorrect.
In my practice, I have encountered remarkably few cat owners who cannot learn to home test.
Together, my clients and I strive to test two to three times daily and administer insulin as needed. The ideal BG range for patients is 75 to 150—the normal range for cats at home.
Fortunately, when diabetic cats consume low-protein diets, they are very resistant to clinical hypoglycemia.
New, long-acting insulin types such as glargine (Lantus) and detemir (Levemir) have become available for human use. Because they are recombinant molecules that have the structure of naturally-occurring human insulin, they are a natural replacement for human insulins manufactured from animal pancreatic tissue.
For cats, however, human insulin is not preferable to bovine insulin, especially protamine zinc bovine (PZI bovine), because the insulin of the cow is molecularly most similar to feline insulin.
I have used all the available insulin types in feline diabetics and find that PZI bovine is the most predictable and gentle. Unfortunately, a major producer is discontinuing the sale of its PZI bovine insulin, causing considerable concern among veterinarians and pet owners.
According to at least one source of high-quality compounded PZI bovine, however, this product will continue to be available in the U.S. and should be used whenever possible.
Fortunately, tight-regulation principles may be used with any insulin. Proper diet and conscientious home testing are the two most critical elements of this protocol.
Tight regulation is capable of returning all feline diabetics to better health, and the majorities I have worked with have escaped dependence on exogenous insulin using the TR protocol.
I believe a new day is dawning in the battle against this frustrating and often fatal disease.
I invite all my colleagues to join me in this new day.
For more information on this protocol, contact the author at firstname.lastname@example.org.
Last update: 11/7/09