Page 247 - Problem-Based Feline Medicine

15 – THE CAT WITH POLYURIA AND POLYDIPSIA 239

by intravenous dextrose once seizures have Monitoring urine glucose is very useful. This can be
stopped to maintain blood glucose. accomplished using poorly absorbent litter material
● Re-evaluate the cat; usually the insulin dose needs such as silicon beads or shredded paper, which allows
to be decreased by 50–70%. Some cats will no collection of urine for testing with a dipstick, or a litter
longer require insulin, because their diabetes is in box glucose detector system such as Glucotest (Purina)
remission. which is added to the box filler, and reacts to urine with
● It is important to check if the cat is being inad- color changes to indicate the level of glucosuria. Some
vertently overdosed. This can occur when differ- owners are able to train the cat to tolerate a dipstick
ent syringes have been dispensed with a different applied to the urine stream during urination.
volume per gradation than was previously used. For Alternatively, some of the urine-soaked litter can be
example, for many brands of syringes, the grada- mixed with water and tested with a dipstick after strain-
tions on a 1 ml 100 U/ml syringe represent 2 U, ing through a cloth.
whereas on a 0.5 ml syringe represent 1 U. If ● Weekly urine glucose monitoring is helpful for
owners are switched to 1 ml syringes, the dose may detecting diabetic remission, especially in cats
be inadvertently doubled, if the same number of treated with lente, NPH or ultralente insulin. Cats
graduations is used to dose the insulin. Similarly, with negative urine glucose should be evaluated for
a switch from syringes designed for U100 insulin to remission.
those for U40 insulin may result in an inadvertent ● With the long duration of action of glargine, there
2.5 times increase in dose. should be minimal periods when blood glucose is
> 14 mmol/L (240 mg/dl), and hence stable cats
Treatment of “healthy” diabetic cats.
should almost always be 0 or 1+ for urine glucose.
● If the cat is not very depressed or dehydrated, start
A value 2+ or greater likely indicates that an
lente, ultralente, PZI or insulin glargine subcu-
increase in dose is required.
taneously.
● Because cats treated with lente, NPH or ultralente
– Use an initial dose of 0.25 U/kg ideal body
insulin usually have hyperglycemia within 6–8 h
weight q 12 h, if blood glucose is between
after insulin administration, which persists until the
12–19 mmol/L (220–350 mg/dl).
next dose, it is not recommended to use urine glu-
– Use an initial dose of 0.5 U/kg ideal body
cose measurements to increase the dose of these
weight q 12 h, if blood glucose is 20 mmol/L
insulins.
(360 mg/dl) or more.
Monitoring fructosamine or glycated hemoglobin
Glycemic control should be monitored using clini-
concentration can be a useful indicator of glycemic
cal parameters (water intake, urine glucose con-
control in cats susceptible to stress hyperglycemia, if
centration, body weight), and at each major
the owner is unable to measure water intake.
recheck, measurement of glucose concentration
Fructosamine concentrations > 500–550 μmol/L (nor-
every 2 h (lente, ultralente) or 4 h (PZI, glargine).
mal < 400 μmol/L) or glycated hemoglobin > 3–4%
Water drunk, urine glucose and blood glucose con-
(normal < 2.6%) are consistent with poor glycemic
centrations are the most useful parameters for
control.
adjusting insulin dose.
● Water drunk of ≤ 20 ml/kg/24 h on canned food or Adjusting insulin dose.
1
≤ 60 ml/kg/24 h on dry food indicates exemplary ● In general, increase the dose by ⁄2–1 U/cat q 12 h
glycemic control. every 1–4 weeks to achieve a nadir glucose con-
● Water drunk is a better indicator of mean blood glu- centration of 7–9 mmol/L (126–162 mg/dl). Once
cose and level of clinical control than is fruc- clinical signs have resolved, and the blood glucose
tosamine concentration. is relatively controlled, a nadir of 5–6 mmol/L can
● Water drunk should be measured at home on at be achieved. Rebound hyperglycemia is a common
least two consecutive days prior to measurement of consequence of aiming for a low nadir too early in
blood glucose concentration. Ideally, an owner the stablization process, especially if using lente,
should keep a daily diary of water drunk. ultralente or NPH insulin.