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Why Does My Veterinarian Want to Test My Dog for Diabetes?

Reviewed by Dr. Celeste Clements, DVM, DACVIM on Tuesday, November 3, 2015
Posted November 03, 2015 in Dog Checkups & Preventive Care

Since diabetes mellitus (“sugar” diabetes) also occurs in people, many dog guardians may be somewhat familiar with the disease (symptoms, diagnosis, treatment, etc.). What you may not be aware of is that the disease occurs in approximately 1 out of every 200 canine patients, according to It is particularly common in middle-aged and older dogs.

What makes diabetes hard to spot?
Fortunately for people, the early signs of diabetes may be more readily recognized, but in our dogs signs like subtle increases in water intake and/or urine output may go undetected. Changes in activity levels and attitude may be overlooked as being normal aging changes in our older dogs. Unfortunately, untreated diabetes in dogs can also cause other serious diseases such as urinary tract infections and cataract formation. Diabetes screening should become a part of routine medical testing as dogs begin to age.
How will my veterinarian test my dog for diabetes?
Since diabetes results in elevated blood glucose (sugar), an abnormally high blood glucose level on a routine blood test certainly raises the possibility that your dog has diabetes. BUT to be considered significant the abnormal reading should be reproduced on a second sample AND the blood should be drawn when your dog has been fasted (has not eaten) in order to rule out normal, post-prandial (after eating) temporary changes in blood glucose.

Because excess amounts of circulating glucose in your dog’s blood stream are filtered out and excreted by the kidneys, finding glucose in a urine sample also significantly increases the likelihood that diabetes is present. However, blood sugar levels can be elevated to twice normal before glucose is detected in the urine (according to AAHA) so this is not a particularly sensitive test and certainly should not be relied upon as a sole screening test for diabetes.

In addition, there can be a great deal of variation in blood sugar levels over the course of even one day, let alone over the course of many weeks. Since a diagnosis of diabetes requires the documentation of a persistent elevation of blood/urine glucose, it becomes important to get a clear picture of what your dog’s blood glucose levels are over a longer period of time. It is important especially if your dog has already been diagnosed with diabetes and you are trying to control the disease with medical management.

Something called a glucose curve or serial blood glucose level can provide insight into what your dog’s blood glucose levels are doing for a longer period of time. But this requires drawing blood on your pet frequently during the assessment period, e.g., every two hours. That means altering your dog’s normal daily routine in addition to specifically adding stress to that equation. So while helpful, serial blood glucose levels still do not paint a picture that is truly representative of what your dog’s levels are doing in his normal, everyday life.

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Mike has more than 35 years of experience in companion animal veterinary practice and is a valued member of IDEXX’s Pet Health Network team since 2013.