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High Blood Sugar in Cats


Hyperglycemia in Cats


The term hyperglycemia refers to higher than normal levels of glucose in the blood. A simple carbohydrate sugar that circulates in the blood, glucose is a major source of energy for the body, of which normal levels range between 75-120mg.


Insulin, a hormone that is produced and released by the pancreas into the bloodstream when glucose levels rise, plays a pivotal role in maintaining the blood sugar levels within normal limits. If insulin concentration is too low or there is absolute deficiency of insulin, levels of glucose rise sharply leading to hyperglycemia.


Some of the causes for hyperglycemia may be pancreatitis, and the resulting inability to produce insulin; normally occurring hormones, especially in female cats; diet; and infections of the body (such as teeth, or urinary tract).


Middle aged and older cats are more at risk for developing hyperglycemia, but otherwise, no breed is particularly disposed to this condition. Neutered male cats are at increased risk. Cats in general are prone to high blood sugar, typically during times of stress, where glucose levels may reach 300-400mg. This is often a temporary increase in blood sugar, and while it warrants further observation, it may not be cause to diagnose chronic hyperglycemia or diabetes mellitus.


Symptoms and Types


Clinical symptoms may vary depending on the underlying disease/condition. Your cat may not be showing any serious symptoms, especially those if the increased sugar is thought to be temporary, hormonal, or stress induced hyperglycemia. Some of the more common symptoms include:


  • Increased thirst (polydipsia)
  • Increased urination (polyuria)
  • Depression
  • Weight loss
  • Obesity
  • Excessive hunger
  • Dehydration
  • Cataract
  • Bloodshot eyes (due to inflamed blood vessels)
  • Liver enlargement
  • Nerve damage in legs
  • Severe depression (in cases of very high blood sugar levels)
  • Non-healing wounds;infection is increased as the excess sugar feeds fungal and bacterial invaders
  • Tissue damage (due to oxidizing [burning] effect of the excess sugar in the tissue)




Other than high stress situations, harmful drug interactions (such as with heartworm medication), and intake of nutritional solutions containing high glucose, the following are potential causes to hyperglycemia:


Low glucose consumption within body leading to high blood levels


High glucose production


Physiological causes

  • Soon after taking meal
  • Exertion
  • Excitement
  • Stress



  • Infections in the body can drive blood sugar levels high
  • Dental infection
  • Kidney infection
  • Urinary tract infection






A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. Your veterinarian will have the blood samples tested immediately for blood sugar levels. In some cases the only abnormal finding will be the raised blood sugar. This is especially true in cases that are linked to temporary conditions, such as stress or hormones. Unless there is some underlying disease/condition present, the blood test results are usually normal.


Urinalysis may reveal higher sugar levels, pus, bacteria, and an excessive number of ketone bodies in the urine, as seen in diabetes mellitus. Low insulin levels accompanied by high blood glucose levels are also indicative of diabetes mellitus. High lipase and amylase enzyme levels indicate inflammation in the pancreas. In some cases higher liver enzyme levels are also present due to fatty deposits in the liver tissue. Abdominal X-rays and ultrasound may provide important information regarding the underlying disease.


More specific tests may be required to diagnose the underlying cause. You will need to give a thorough history of your cat's health, onset of symptoms, and possible incidents that might have led to this condition, such as stressful events that might have cause the spike in blood sugar. The history you provide may give your veterinarian clues as to whether secondary symptoms are being caused by underlying organ disorders, such as undiagnosed diseases of the pancreas (e.g., pancreatitis, amyloidosis).


If your cat has had any previous infection in the body, you should tell your veterinarian about it, as it may still be present and causing glucose levels to remain high.


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