Noting symptoms is the first step for diagnosing diabetes in your cat. Cats are undemonstrative; some signs may be spotted by the owner with difficulty.
The list of cat diabetes symptoms:
- Polyuria (increased urination) will be noticed from the increased need to change the cat’s litter.
- Similarly you will have to fill in its water bowl more often to quench its polydipsia (increased thirst)
- Lethargy shows up through decreased interaction with the environment
- Unkempt hair coat is linked to decreased grooming frequency
- Polyphagia (increased hunger )
- Neurologic syndrome of weak legs: stance on the hocks, hind limb weakness, loss of the cat’s ability to jump
These signs do not take into account diabetes complications such as the dangerous diabetic detoacidosis (DKA).
Glucose goes into the urine when its blood concentration exceeds 290 mg/dL (16 mmol/dL). Glucose increases urine osmolarity and attracts water, thus increasing urine volume = polyuria. The cat drinks more to avoid dehydration = polydipsia.
Cells need insulin for making use of glucose. Insulin resistance and insulin deficiency prevent the cells from using glucose and make them look for other sources of energy such as proteins. The organism cannot find all the energy it needs: the cat becomes lethargic. It uses a lot of its proteins for meeting its needs: the cat loses weight and becomes hungrier.
The causes of diabetic neuropathy have not been fully explained yet. Neurologic symptoms may originate from a direct toxicity of elevated glucose concentrations on the nerves and/or from lesions in the smaller vascular vessels and/or from complex immune mechanisms.
As diabetes is curable disease, when taken care of early, it is crucial to diagnose it early for giving the treatment the best chance of success. But, the diagnosis is far from simple, mainly due to cats sensitivity to stress.
It will always start by the identification of the symptoms during the cat physical examination and the owner interview. As the signs are not specific to diabetes, the vet will perform lab analysis to confirm her suspicion.
The cats are prone to develop hyperglycemia when stressed, which is often the case at a veterinary consultation. In some cases, the hyperglycemia reaches the 290mg/dL (16 mmol/L) threshold and makes glucose pass in the urine. Thus, fasting blood glucose or glucose urine measurement will only be used for ruling out diabetes if they are negative, but cannot confirm the diagnosis if they are positive.
Your vet may ask you to perform several urine glucose measurements at home, where your cat will not be exposed to stress.
Alternatively, the vet may perform a serum fructosamine test, which is rapid and easy to implement. Fructosamines are proteins irreversibly bound to glucose: glycated proteins. They show evidence of blood glucose concentration during the life span of the proteins (about two weeks). The more fructosamines, the higher the glucose concentration during the last 14 days. The fructosamine test estimates the mean blood glucose concentration, and thus of the severity of the cat diabetes. The fructosamine serum concentration for healthy cats ranges from 190 to 365 µmol/L. Values exceeding 500 µmol/L demonstrate a poor control of diabetes. However, in case of stressful episodes within the former two-week period, the fructosamine test will show abnormally increased values.