Background

Simon is a, 11 year domestic long hair “alley cat”. Simon came to our clinic because of increased urination and drinking (polyuria/polydipsia) and inappropriate urination.  As part of initial work-up, a urine sample was analysed to rule out the most common medical forms of inappropriate urination including infection, inflammation, and crystals.  Unfortunately his urine sample came back as being filled with glucose (sugar) as a condition called glucosuria.

What causes glucosuria?

Glucose in the urine happens when blood glucose levels “surpass renal threshold” – in other words there is too much glucose present in the blood stream forcing the extra to be peed out.  This continual flushing of glucose by the body leads to the increased water intake and urination.  There are very few diseases associated with the presence of glucose in the urine as we either have to see an increase in total blood glucose levels or damage to the kidneys that causes the renal threshold to be lower.  Kidney damage can include acute toxin ingestion (such as lily poisoning) however the most common disease we diagnose associated with glucosuria is diabetes mellitus.

What is diabetes mellitus?

Diabetes mellitus is caused by a lack of insulin production.  There are two subtypes of diabetes, type I and type II. 

• Type I diabetes, also known as juvenile diabetes, is seen in dogs and people.  It is a type of diabetes where the pancreas tissue is destroyed, usually by auto-antibodies. 
• Type II diabetes, also known as insulin resistant diabetes, is seen in cats.  Type II diabetes reflects more a pancreas burn out rather then complete destruction.

What causes diabetes in cats?

Diabetic cats generally have a functional pancreas but for a variety of reasons, the pancreas is unable to meet the body’s insulin needs and, eventually, becomes burned out.  It is now known that any cause of inflammation in the cat’s body can predispose them to diabetes.  Three of the most common sources of inflammation include:

• Obesity: As scary as it sounds, body fat is not just hanging around as excess energy stores as once thought.  Current research has shown that fat tissue makes its own inflammatory mediators so, if present in too large amounts, can become a source of inflammation
• Pancreatitis: Pancreatitis was once thought to be a rare disease in cats.  This is because (a) cats, unlike people and dogs, typically have a smouldering chronic form of the disease and (b) the tests we had available to diagnose it were not very sensitive.  Newer blood tests have been developed that look for cat-specific pancreatitis markers and better ultrasound machines means that looking at this organ on imaging is now possible
• Dental disease: The “evil gingivitis” is inflammation of the gums.  If severely inflamed, apart from being painful, can affect other organs.  Dental disease is also affected by diabetes as the extra glucose in circulation makes its way to the saliva where it becomes a feast for mouth bacteria creating a vicious cycle of infection and inflammation.
• Urinary tract infection: UTIs are very common in diabetic cats because of the high sugar levels.  Although they may not, on their own, cause diabetes they may help “tip the balance” on an already stressed body.

What do we look for when assessing diabetes?

Focusing on Simon’s diabetes the blood chemistry changes that we look at include:

• Blood glucose: Cat normal is approximately 4 – 8mmol/dL.  Cats can have high blood sugar levels because of stress but values greater then 20mmol/dL are usually not caused by stress.
• Fructosamine: This is a different type of sugar in the body that changes slowly over time therefore fructosamine provides a 14 sugar average.
• Liver enzymes: The liver is the organ of metabolism.  As diabetics have improper metabolism, the liver enzymes often jump up in response to the increased work load
• Pancreas damage markers: The spec fPL is a cat-specific marker for pancreatitis.
• Urine culture: to rule out concurrent infection

What were Simon's values?

• Blood glucose: 29.9mmol/dL (normal range is 4.0 – 8.0mmol/dL)
• Fructosamine: 567umol/dL (normal range is 191 – 349umol/dL)
• Liver enzymes:
  • ALT: 102IU/L (normal range is 28 - 76IU/L)
  • ALP: 80IU/L (normal range is 0 – 62IU/L)
• Pancreas marker: 3.5ug/L (normal range is less then 3.5ug/L)
• Urine culture: E.coli bacterial infection present

How do we treat Simon?

Given this lease on life, Simon was started on care that reflects the most common reasons for diabetes in cats:

• Dental care: Even before starting Simon on insulin and getting him “regulated”, he was placed under anesthetic and his teeth underwent a thorough cleaning.  Any problem areas (including painful cavities) were removed.
• Weight loss: Simon was started on a low calorie, novel carbohydrate diet (Purina OM).  This diet contains more complex carbohydrates to avoid blood sugar spikes.  Simon was also started on canned food as canned food is richer in protein then dry diets.
• Insulin therapy: Simon was started on the long-acting human insulin Glargine (Lantus®).  His new owner was shown how to monitor his blood sugar levels at home using a human glucometer so that his insulin dose could be adjusted as needed.
• Antibiotics to treat his infection
• Supportive care: B12 injection and anti-oxidant supplements were prescribed for Simon.  Both of these help support the pancreas and keep it happy

How did Simon do with treatment?

After approximately 3 months on insulin therapy, Simon’s pancreas decided it was going to work again and he went into diabetic remission.  6 months after this happy event, he is still in remission and being maintained on a maintenance diet plan and ongoing B12 to help decrease the chances of reverting back into a diabetes state.