Page 131 - Clinical Small Animal Internal Medicine

12 Diabetes Mellitus in Dogs and Cats 99

VetBooks.ir Results of serial blood glucose concentration testing ● If duration of action of NPH or lente insulin apprears to
determine whether the insulin dose should be
be substantially less than 12 hours and signs of poor
increased, left unchanged, or decreased. Be conserva-
control persist, try detemir if the dog is >5–10 kg (note
tive with dose increases because severe clinical hypo- lower dose with detemir). If insulin sensitivity is nor-
glycemia kills dogs. mal, dosing dogs weighing <5–10 kg can be problem-
Dogs are considered to have stable glycemic control atic with detemir. If necessary, it can be diluted with
●
when the following criteria are all met over 2 months: saline or sterile water or a special diluting solution
(a) fluctuation of insulin dose by 1 unit or less, (b) from the manufacturer. Alternatively, glargine 300 U/
water drunk <70 mL/kg/day, (c) stable body weight, ml (Toujeo) appears to be useful in some poorly con-
and (d) absence of ketonuria. The period required to trolled dogs and is best combined with a low carbohy-
achieve stablization ranges from 3 to 10 months drate diet.
(median 7 months).

significant weight loss in some diabetic dogs, and thus Exogenous Insulin Resistance
are not suitable for most lean or underweight dogs. A Insulin resistance means decreased sensitivity to endog-
variety of commercially available, nonprescription grain‐ enous or exogenous insulin. Endogenous insulin resist-
free diets are available which are lower in carbohydrate ance is a major factor in the pathogenesis of type 2
and higher in protein and fat, but have not yet been used diabetes in cats, when superimposed on reduced beta‐
in clinical trials with diabetic dogs. Dietary fat restriction cell function. Insulin resistance should be investigated in
(<30% ME) should be considered for diabetic dogs with dogs or cats when insulin therapy does not have the
concurrent chronic pancreatitis or persistent hypertri- expected effect – animals are consistently hyperglycemic
glyceridemia. It is usually recommended that insulin be despite insulin doses of greater than 1–1.5 units of insu-
given within one hour of a meal and in most cases, for lin per kg body weight per dose (not per day).
convenience, it is given at the time of insulin injection. Insulin resistance may incorrectly be diagnosed when
The primary goal of treatment in feline diabetes is to
obtain remission; that is, maintenance of euglycemia insulin is stored, handled or administered improperly. It
can also be misdiagnosed when duration of insulin action
without the need for insulin therapy or oral hypoglyce- is too short to maintain good glycemic control and results
mic drugs. Remission is possible in 80% or more of newly in marked hyperglycemia prior to each insulin injection,
diagnosed feline diabetics if managed to achieve normal despite increasing dose. Hyperglycemia following a
or near normal blood glucose concentrations soon after hypoglycemic episode is often attributed to a rebound
diagnosis. Probability of remission is increased when a phenomenon associated with secretion of counterregula-
low‐carbohydrate (<15% ME), high‐protein diet (Hills® tory hormones, termed a Somogyi phenomenon.
m/d, Purina® DM, or others) is used in combination with However, evidence for this pathogenesis as a cause of
long‐acting insulins such as glargine or detemir adminis- hyperglycemia following hypoglycemia is lacking in vet-
tered twice daily. Lower remission rates are reported erinary and human medicine. This pattern of hypoglyce-
using PZI or porcine lente insulin or when a moderate‐ mia followed by marked hyperglycemia is a relatively rare
carbohydrate diet is fed. Rapid institution of excellent occurrence in cats treated with glargine or detemir (1.5%
glycemic control, ideally in conjunction with home mon- of blood glucose curves), and inadequate duration of
itoring, contributes to remission, while institution of insulin action should be suspected rather than attribut-
tight control six months or more after diagnosis is asso- ing the hyperglycemia to a rebound effect and associated
ciated with significantly lower rates of remission (84% insulin resistance. Persistent hyperglycemia also causes
versus 34%) (Box 12.2). Because remission often occurs insulin resistance which likely explains why insulin dose,
within 4–8 weeks of therapy if cats are managed opti- after an initial increase over 1–2 months in newly diag-
mally, weight loss is not a major factor in achieving nosed animals, typically decreases over a similar period
remission but it is critically important for maintaining in both dogs and cats which remain insulin dependent.
remission. Eating does not need to be coordinated with Acromegaly is a syndrome of excess growth hormone
insulin administration, especially if a low‐carbohydrate production, which typically causes profound endoge-
diet and long‐acting insulin are used. Type and amount nous insulin resistance. It is rare in dogs, and caused by
of food and snacks should be consistent each day, and mammary tissue oversecretion. It is relatively common in
snacks must be low carbohydrate.
cats, with at least 25–30% of poorly controlled diabetic