ACCREDITED CPD
Management of
Diabetes Mellitus
Marlies Bohm BVSc DSAM MMedVet(Med) DipECVIM-CA
Diagnosis:
The animal should have a consistent history ie pu/
pd, pp and weight loss. Dogs are usually straightforward. Cats are a little trickier. Stress can cause the
blood glucose to go well above 20 mmol/l AND can
spill over into the urine if you annoy the cat for long
enough. Usually if the blood sample collection is the
only stressor, there won’t be enough glucose in the
urine to confuse you. Occasionally dogs can do this
too. The renal threshold for glucose in cats is 12 – 15
mmol/L and in dogs is about 10- 12 mmol/L. Remember that alpha 2 agonists (xylazine, medetomidine)
cause a glucosuria.
If your cat has ketones AND glucose in the urine, you
can probably believe the high serum glucose is due to
diabetes and start insulin.
If in doubt, run a fructosamine.
Treatment
Before you start treating, determine if the patient has
any complications of diabetes. Some of these can
cause insulin resistance and make stabilisation a lot
more difficult.
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Ketoacidosis – if also inappetant and vomiting, a
ketoacidotic patient should be hospitalised, placed
on IV fluids and initially treated with regular insulin. You also need to search for the trigger for the
ketoacidosis (often a concurrent infection/inflammatory process.
Hypertension – control with amlodipine and / or an
Angiotensin converting enzyme inhibitor (ACEi).
Proteinuria – if you’ve excluded a urinary tract infection and an ejaculate in the urine, your patient will
benefit from ACEi therapy. Diabetic nephropathies
are common in humans and there is a huge body
of evidence supporting the benefits of ACEi for affected people.
Cataracts – 80% of dogs with DM will develop
these, often acutely. Diabetic cats will also eventually develop lens opacities but they don’t usually affect sight noticeably.
Uveitis – usually lens (cataract) induced. Initially
treat with Maxidex, Maxitrol or similar. Remember
that there will be some systemic absorption of the
corticosteroid which will affect your patient’s insulin
requirements. Ideally remove lens once patient is
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stable.
Peripheral neuropathy – most commonly observed
in cats who develop a plantigrade stance.
Screen for common concurrent diseases/conditions:
• pancreatitis
• infections (abscesses in cats)
• urinary tract infection and bladder stones
• hyperthyroidism (cats)
• dioestrus – progesterone causes insulin resistance.
Intact female dogs will be easier to stabilise if they
are sterilised.
• chronic renal failure
°° NOTE - glucose is dissolved in the urine - and
the SG measures dissolved solute. The SG of a
diabetic cat with concurrent CRF may not be
below 1.035 if there is a strong glucosuria. As a
general rule of thumb a 2% or 4+ glucosuria will
increase the urine SG by 0.008 to 0.010 when
SG is measured using a the refractometer.
°° If your animal has another reason to be pu/pd
(eg CRF, hyperthyroidism, Cushing’s etc) you
cannot use this sign to determine the efficacy
of the insulin.
Initial stabilisation
Cats:
• Glargine: start on 0.25 IU/kg bid
• PZI (Protamine zinc insulin): 0.2-0.5 IU/kg bid, maximum total dose of 1 IU per cat per injection
• Caninsulin: start at 0.25-0.5 IU/kg bid with a maximum