Blood glucose monitoring
Editor's Note: In a continuing series of articles, DVM Newsmagazine has teamed up with the American College of Veterinary Internal Medicine, (ACVIM) to bring you the latest in research abstracts on a variety of topics. Every month, an ACVIM diplomate will summarize, in abstract form, the latest research in specialty fields. These articles are coordinated with the help of Dr. Ron Lyman, Ft. Pierce, Fla.
"Many inexpensive blood glucose monitoring systems have been used by human diabetic patients for accurate assessments of their blood glucose levels for many years.
Recently, pet owners have been using these devices on the ears of dogs and cats with diabetes to get immediate and accurate blood glucose samples on their diabetic pets. This has improved quality of glucose regulation and accurate assessments of insulin requirements."
Management of diabetes mellitus in dogs and cats has always been a challenge for the pet owner and the veterinarian.
When an animal is first diagnosed with diabetes mellitus or develops a crisis due to dysregulation, pets are typically evaluated in a hospital setting, at which time glucose curves are performed from venous blood samples at regular intervals to evaluate the animal's response to insulin. Once an acceptable insulin dosage is determined, the pets are sent home to their natural environment, where the pet owner's subjective analysis (or an actual measurement) of the dog or cat's water consumption, appetite, weight, urine glucose and urine ketone levels and are used to determine glucose control.
Close monitoring of the pet's activity, diet and consistent schedules are also very helpful in controlling or maintaining consistent blood glucose levels at home.
Change over time
Because the patterns established from blood glucose curves done in the hospital, in a stressful and unnatural environment, are used to determine the insulin dosage the pet will go home on, it is rare if the prescribed insulin requirements do not change over time at home.
Insulin dosages are selected by assuming that the glucose curve is representative of what occurs in the pet's body once it leaves the hospital. In fact, it has been shown that there is a large variation in the day-to-day results of serial blood glucose curves in diabetic dogs.
This has very important clinical implications, especially when a single predetermined dose of insulin is prescribed based on such curves. (Proceedings of the 19th ACVIM Forum, Abstract # 101).
Traditional monitoring of glucose control
Traditionally, the mainstay of home management of blood glucose and insulin dosages involves the owner and veterinarian's interpretation of urine glucose measurements.
There has never been a debate about the disadvantages of urine glucose monitoring.
For example, the urinary bladder can store urine for several hours; therefore it is rarely an accurate reflection of blood glucose at a particular time. Obtaining a urine sample is not always a simple task, therefore is often not performed on a consistent basis. Monitoring urine glucose is virtually impossible in an outdoor-only cat or in a dog or cat with primary renal glucosuria. (Schaer, M. A justification for urine glucose monitoring in the diabetic dog and cat. J Am Anim Hosp Assoc 2001;37:311-312.)
Inability to differentiate hyperglycemia due to the Somogyi phenomenon vs. true hyperglycemia can be a deadly consequence of using urine glucose as the daily determinant of glucose control. Nevertheless, when the client is compliant and other monitoring parameters such as weight, degree of polyuria and polydipsia, serum fructosamine levels and regular glucose curves in conjunction with urine glucose monitoring, it has been an acceptable method of monitoring for many years.
At-home monitoring of blood glucose
For many years, inexpensive blood glucose monitoring systems have been used by human diabetic patients for accurate assessments of their blood glucose levels.
There is a trend developing in veterinary medicine: using a blood glucose meter designed for human diabetics as a simple, rapid, pain-free method of getting immediate and accurate blood sugars on diabetic pets. The advantages of such a technique are clear: the pet is in its natural home environment, thus diminishing the role of stress on blood glucose values. Samples can be obtained easily in dogs and cats using a device purchased in any pharmacy by performing a simple ear stick technique to obtain a blood sample. Repeated sampling is easily performed. The results are a true measure of blood glucose at the time of the test (Proceedings of the 19th ACVIM Forum, Abstract #100).
The test is simple to do and owner compliance is likely. The day-to-day variations of blood sugar in pets can be taken into account and insulin dosages can be adjusted on a daily basis, if need be. These methods have been described and have improved quality of glucose regulation and accurate assessments of insulin requirements. (Reusch CE, Wess G, Casella M: Home monitoring of blood glucose concentration in the management of diabetes mellitus. (Comp Cont Ed Pract Vet 2001;23:544-556.)
It is important to remember, however, that this testing method, although an excellent advancement in management of diabetes mellitus for veterinary patients, should not be the sole method of evaluation.
The veterinarian should make treatment decisions with the client on a regular basis based on home blood glucose monitoring in and all other aspects of diabetes management such as the patient's weight, degree of polyuria and polydipsia, serum fructosamine levels, and some urine glucose and ketone monitoring.