Canines and felines with diabetes mellitus require a considerable investment in time for both the client and clinician.
Canines and felines with diabetes mellitus require a considerable investmentin time for both the client and clinician.
Veterinary endocrinologists point out that the changing status of pancreaticfunction and factors such as the development of antibodies toward insulinwill result in changing exogenously administered insulin requirements inalmost all patients as time passes.
All parties involved in the care of these patients should also be awarethat concurrent disease entities (e.g. urinary tract or other infections,hyperadrenocorticism, hypothyroidism, hyperthyroidism) and/or physiologicfactors such as changing exercise patterns or food intake also alter insulinrequirements. Until pancreatic islet cell implants or totally self-containedintegrated glucose monitor/insulin pumps are perfected, the best optionis to set up a program where both the client and doctor follow the resultsof diabetic management. This article will discuss some relevant recent publicationson this subject.
The first requirement of such a program is the observation of the patientat home by the clients/caretakers. The successfully managed diabetic willprobably be eating well, maintaining body weight, feeling bright and alert,and hopefully will not be showing signs of neuromuscular (posterior paresisin the cat) or ophthalmic (cataracts) complications. A key positive observationis client perception that there is control of polyuria/polydipsia. Roughlyspeaking, this means less than 90 ml/kg/day of water consumption in thecanine or <45 ml/kg/day in the feline. The caretaker should report nosuspected episodes of hypoglycemia if all is going well.
In a recent article (pages 311-312, JAAHA, July/August 2001, Vol 37),Dr. Michael Schaer reminds us that there are important reasons to monitorurine glucose on a regular basis at home in these patients.
This is one practical method of monitoring day-to-day variations in glycemiccontrol. It is especially important in identifying patients that may beexperiencing a reduction in their insulin needs (i.e. the transient felinediabetic or the Cushing's/diabetic canine that is producing less cortisoldue to effective therapy for hyperadrenocorticism). This method has receivedscant attention in recent literature, but it has no peer or replacementin its ability to reveal ketonuria when Keto-Diastix (Bayer Corp.) are usedto test the urine. It brings the client in touch with the concept that closemonitoring is vital to their pet's welfare, and demonstrates to them that,in fact, urine glucose, and thus blood glucose levels, are always in flux.In certain selected patient/client combinations, urine glucose determinationscan be used to modify daily insulin dosages based on predetermined limitationsspecified by the attending clinician. Schaer has a detailed and eloquentdiscussion of this method in his article.
These tests may also signal changing insulin needs by identifying progressivelyhigher urine glucose levels, leading the clinician to perform the next testwe will discuss.
Blood glucose curve
The "blood glucose curve" is the method most commonly discussedin relation to insulin dosage determination and modification.
It can be used to document if hypoglycemia or "Somogyi" phenomenonare occurring. It can be used to re-evaluate insulin type selection or dosagein cases where clinical signs are flaring up or concurrent diseases appear.Blood glucose curves may also be used in the initial selection of insulindosages and/or on a regular basis to follow up glycemic control. It is importantto realize that these curves may be affected by changes in stress, exerciseand food consumption, especially if they are performed in a hospital setting.In addition, the clinician should consider ruling out secondary factorscontributing to poor diabetic regulation (e.g. urinary tract infection,hypothyroidism, Cushing's, etc.) before using this method to change an existingdosage regimen.
In the 2001 ACVIM Forum Proceedings abstract #101, Drs. Fleeman and Randreport results from 12 hour blood glucose curves performed on 10 canineswith spontaneous diabetes mellitus. Results were recorded over two consecutivedays on three different occasions for each patient.
Based on the curve results, a theoretical recommendation to increase,decrease or maintain the current insulin dosage was developed. The resultswere so varied that 27 percent of the time the results on day 1 resultedin an opposite recommendation from the results on day 2. Thus, especiallyin patients with control of clinical signs, the clinician may not wish toproceed solely on the results of this method.
Some clinicians and extremely cooperative patient/client combinationsare beginning to sample drops of blood with the contemporary lance and "athome" glucose measurement devices.
In the 2001 ACVIM Forum abstract #149, Drs. Cohn et al compare resultsfrom several of these devices to those of a standard dry chemistry unit.They note that the accuracy of each device was lower at values less than100 mg/dl, with median differences between dry chemistry and the devicesranging from 26 mg/dl to (+) 40 mg/dl. All devices tested had occasionalreadings markedly different than the dry chemistry determination "whichcould have led to clinically inappropriate treatment choices. "Thedoctor and client should probably double check low, low normal or unexpectedvalues obtained from these devices before adjusting insulin dosages basedon these tests.
Finally, information on glycemic control over the preceding weeks canbe obtained by the use of fructosamine or glycosylated hemoglobin tests.
Schaer points out that these tests "will not assist in identifyingany particular patient's day-to-day changing needs for more timely insulindosage adjustments, especially in overdose situations,"and suggeststhat diabetic control be based "on the combined utilization of clinicalsigns, blood glucose curves, glycosylated blood tests and urine glucosemonitoring."