Page 865 - Small Animal Internal Medicine, 6th Edition

CHAPTER 49 Disorders of the Endocrine Pancreas 837

glucose results are similar when blood for glucose determi- glycemic control, another change in therapy based on an
nation is obtained by the ear and pad prick technique and educated guess should be performed, and serum fructos-
VetBooks.ir venipuncture. However, blood glucose results obtained by amine should be measured again 2 to 3 weeks later.
PBGM devices designed for use in humans with diabetes
INSULIN THERAPY DURING SURGERY
may overestimate but more commonly underestimate the
actual blood glucose values obtained with reference methods. Approaches to managing the diabetic cat and dog during
This inherent error must be considered when blood glucose surgery are similar and are discussed on page 813.
results obtained by these PBGM devices are interpreted. One
exception is the AlphaTRAK2®(Abbott Laboratories). Accu- COMPLICATIONS OF INSULIN THERAPY
racy of this portable glucometer is very good in cats, but Complications of insulin therapy are similar for diabetic
glucose values may be higher or lower than glucose values dogs and cats and are discussed on page 824. The most
measured by benchtop methods on the same blood sample, common complications of insulin therapy in the diabetic cat
forcing the veterinarian and client to accept the blood are recurring hypoglycemia and diabetic remission; incor-
glucose concentration at face value. There are several excel- rect assessment of glycemic control caused by stress-induced
lent online sites that demonstrate home blood glucose moni- hyperglycemia; insulin overdose; short duration of effect of
toring techniques for the owner of a diabetic cat (e.g., Abbott NPH, lente, and, less commonly, PZI, insulin glargine, and
Laboratories website for the AlphaTRAK2®). The clinician or insulin detemir; prolonged duration of effect of PZI, insulin
technician should allow ample time to teach the technique to glargine, and insulin detemir; and insulin resistance caused
clients willing to give it a try and provide advice regarding by concurrent inflammatory and hormonal disorders, most
how often to measure blood glucose concentration and when notably chronic pancreatitis. Evaluation of a serial blood
to monitor blood glucose concentration in relation to the glucose curve is usually required to identify the underly-
time of insulin injection. Use of the ear and pad prick tech- ing problem. A common mistake when insulin glargine or
nique in cats has produced excellent results. Stress is often insulin detemir is evaluated in a poorly controlled diabetic
significantly reduced, and the accuracy of blood glucose cat is that only one or two blood glucose concentrations are
measurements is improved. Problems with at-home moni- measured during the day under the assumption that insulin
toring of blood glucose concentrations include overzealous glargine and insulin detemir have a slow, sustained absorp-
clients who start monitoring blood glucose concentrations tion that results in a relatively flat blood glucose curve (Fig.
too frequently, insulin overdosing and hypoglycemia caused 49.16, A). Unfortunately, the absorption pattern and the
by clients who interpret blood glucose results and adjust the duration of effect of insulin glargine and insulin detemir are
insulin dose independent of input from the veterinarian, unpredictable in diabetic cats (see Fig. 49.16, B), and inter-
difficulty obtaining blood from the ear or pads, and cats pretation of only one or two blood glucose concentrations
who do not tolerate manipulation and pricking of the ear can be misleading. A complete serial blood glucose curve as
or pads. discussed on page 819 should always be done in a diabetic cat
with persistence of clinical signs and poor diabetic control,
Role of Serum Fructosamine in Stressed regardless of the type of insulin being administered.
Diabetic Cats
The use of serum fructosamine concentrations for assessing Stress Hyperglycemia
control of glycemia is discussed on page 818. Serum fructos- Transient hyperglycemia is a well-recognized problem in
amine concentrations are not affected by acute transient fractious, scared, and otherwise stressed cats. Hyperglyce-
increases in blood glucose concentration. Unlike blood mia develops as a result of increased catecholamine con-
glucose measurements, evaluation of serum fructosamine centrations. Blood glucose concentrations typically exceed
concentrations in fractious or stressed diabetic cats provides 200 mg/dL in affected cats, and values in excess of 300 mg/
reliable objective information on the status of glycemic dL are common. Stress hyperglycemia can significantly
control during the previous 2 to 3 weeks. In fractious or increase blood glucose concentrations in diabetic cats
stressed cats, the clinician must make an educated guess as despite the administration of insulin—an effect that compro-
to where the problem lies (e.g., wrong type of insulin, low mises the clinician’s ability to accurately judge the effective-
insulin dose), make an adjustment in therapy, and rely on ness of the insulin injection. Frequent hospitalizations and
owner perception and changes in serum fructosamine to venipunctures for monitoring blood glucose concentrations
assess the benefit of the change in treatment. Serum fructos- are the most common cause of stress hyperglycemia. Blood
amine concentrations can be measured before and 2 to 3 glucose concentrations can remain greater than 400 mg/dL
weeks after insulin therapy is changed to assess the effective- throughout the day despite administration of insulin. Failure
ness of the change. If changes in insulin therapy are appro- to recognize the effect of stress on blood glucose results
priate, the client should observe improvement in the severity may lead to the erroneous perception that the diabetic cat
of polyuria and polydipsia, and serum fructosamine concen- is poorly controlled. Insulin therapy is invariably adjusted,
tration should decrease by more than 50 µmol/L. If the often by increasing the insulin dose, and another blood
serum fructosamine concentration is the same or has glucose curve is obtained 1 to 2 weeks later with essentially
increased, then the change was ineffective in improving the same results. A vicious cycle ensues, which eventually