Is Subclinical Diabetes a Dangerous Condition for your Dog or Cat ?


Your vet will diagnose your pet has diabetes because its blood glucose is elevated and it displays the classical symptoms of diabetes : polyuria (increased urination), polydipsia (increased thirst), lethargy, unkempt hair coat, polyphagia (increased hunger), weight loss (dogs) neurologic symptoms (cats).

The issue here is that measuring accurately blood glucose in pets is not that easy. Moreover, the limit between symptomatic and asymptomatic is not clear-cut and is subject to the interpretation of the vet or the owner. The question therefore is when the owner or the vet should start worrying for a prediabetic pet and taking action, for preventing discomfort and complications.


Diagnosis uncertainties

In theory, symptoms onset takes place when blood glucose starts spilling into the urine. That means the part of the blood glucose that is above a certain threshold (the renal threshold = 200 mg/dL for dogs or 290 mg/dL for cats) is eliminated via the urine.

The vet has several choices for ascertaining his diagnosis:

  • sampling blood and measuring glucose in fasted animals: since there is a lot of variations according to the time of the day and the level of stress of the pet, the measurement usually needs to be repeated several times for several days
  • testing glucose in the urine: if positive, it is the indisputable proof of glucose leakage in the urine. However, this test is not as sensitive as one might expect and false negative are frequent. It leads to under diagnosing the disease
  • the fructosamine test measures the long-term (2-3 weeks) level of glucose in the blood. It is a very useful test in case the vet suspects there might be stress-induced hyperglycemia

As for any other chronic disease, the clinical assessment is difficult too. Of course, the pet will not tell what it feels. The diagnosis is based on examination of the pet by the vet and on the description by the owner of the dog or cat behavior. It often requires a very attentive observation to see these subtle changes in the pet behavior. How would an owner notice that a cat is drinking a little bit more than a few months ago, or that an outdoor dog is less active ? Especially if she is professionally active and not at home for a large part of the day.

We have seen that the limit between clinical diabetes and prediabetes is not very precise. In this case, would it be a good idea to try to treat the subclinical stage of the disease ?

Prediabetes in human medicine

In human medicine, prediabetes is considered as a risk factor, not only for developing diabetes, but also for other serious diseases such as heart disease.

90% of human diabetic patients have the type 2 of the disease. Their diabetes is caused by a resistance to insulin: their blood glucose is not as well regulated by insulin as it used to be. They need more insulin to achieve the same results.

Type 2 diabetes is more frequent in overweight/obese people or those who are not doing enough physical activities. Women who have had gestational diabetes are also at increased risks.

Prediabetes is reversible if preventative measures are taken. They are: losing weight ( 5 to 10% of the initial weight); being physically active, reducing food fat.


The recommendations in veterinary medicine

Veterinarian will usually speak about subclinical diabetic pets instead of prediabetic pets. The AAHA (American Animal Hospital Association) has issued guidelines on how to manage subclinical diabetic cats and dogs


Cat diabetes is very similar to human diabetes. It is a type 2 diabetes that can be reversed if treated early enough. As for humans the medical prescription will include a weight loss program. The weight loss should be limited to 1 to 2 % per week. The new diet will contain as little carbohydrate as the cat will accept to eat, have less caloric density. The cat will be given free access to drinking water. Canned food is preferred because of the additional quantity of water it provides and of the improved palatability.

Increased physical activity would be beneficial. But everybody knows that stimulating a cat for doing some sport is not….let’s say….very easy !!


Dog diabetes is type 1 diabetes. That is the destruction of the cells in the pancreas that produce insulin. It is not reversible. The process can be slowed down by limiting the toxicity of glucose to the pancreas cells i.e. limiting blood glucose increase.

The treatment will consist of helping the pre-diabetic dog reach its ideal weight. A diabetic dog may be obese, but it is often underweight as a consequence of the disease.

What is very important is to limit the postprandial hyperglycemia (dogs are much more prone to postprandial hyperglycemia than cats). Thus, to limit the important increase in blood glucose that follows food intake, the vet will advise the dog makes some exercise or go for a walk after feeding.


Prediabetes is a condition where the dog or the cat has elevated blood glucose but does not suffer from the symptoms of diabetes. This subclinical diabetes requires some attention though. The pet's diet, especially, needs often to be adapted.
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