Cat & Dog - Diabetes Mellitus - Sugar Diabetes - Testing and Monitoring

This handout should be read in conjunction with the handout on Dog - Diabetes mellitus and Cat - Diabetes mellitus.

Sugar diabetes or diabetes mellitus is a not uncommon disease of overweight, middle aged pets.

What are the usual signs?

Weight loss, increased appetite, thirst and urination.  A tentative diagnosis is based on these signs and a simple urine test to detect sugar.  Once a provisional diagnosis has been made a definitive diagnosis will depend upon further tests.

What are these tests?

Tests usually involve a complete blood count (CBC) (which includes white cells, red cells and platelets) a serum biochemistry profile and a full urine analysis.

If the condition is suspected as a result of the signs of weight loss with increased appetite, thirst and urination, why cannot the condition be confirmed just on blood sugar and the presence of sugar in the urine?

Fasting blood and urine results showing elevated glucose levels are essential for the diagnosis of diabetes mellitus.  Further screening tests often give us additional information regarding the animal's general health and may indicate complicating conditions which may influence the line of treatment.  For example, diabetic animals are more prone to infections as a result of the diabetes and the CBC often will give an early indication of this. Other problems can also be picked up with these tests.

Serum, the liquid portion of the blood contains many substances including glucose, enzymes, fats, proteins and carbohydrates together with metabolic waste products.  The determination of the serum glucose level plays a major role in the definitive diagnosis of diabetes mellitus.

Are these tests accurate?

Cats, and to a lesser extent, some dogs, can present problems since serum glucose concentrations are often raised due to stress of the procedure.  In addition blood glucose is also mildly elevated for several hours following a meal.  Therefore confirmation of diabetes may require several blood samples collected over a period several days.

I have heard that fructosamine tests are more accurate.  Can they be done?  

Yes.  Diabetes may be diagnosed by an elevated serum fructosamine result.  Fructosamine is formed as a result of the binding of glucose with certain proteins in the blood.  The higher the blood glucose the greater the amount of fructosamine formed.  Fructosamine can be measured from a single blood sample.  Unlike glucose it is not affected by the stress level of the animal.  It is an extremely useful test and acts as an indicator of the average blood glucose concentration over the previous two to three weeks.  It is therefore useful for long term monitoring of diabetic patients.

Why has fructosamine not replaced glucose tests?

Fructosamine will reliably indicate that elevated blood glucose levels have been present for at least 14 days prior to the test.  It also indicates how well stabilised the patient is when under treatment with insulin.  It does not detect recent fluctuations in blood glucose and therefore cannot be used to calculate daily insulin requirements.  For this a daily blood glucose estimation is still required.

What about urine tests, are they not important?

Prior to the development of simple, accurate blood glucose tests, which many owners use at home to monitor their diabetic pet, daily insulin estimation depended upon the amount of urine glucose present and they are important for stabilisation.

What is involved?

The test is very simple once a urine sample has been obtained.   The urine container should always be very clean to ensure the results are accurate.  Dogs are usually more cooperative than cats, although today there are special cat litters available that allow acceptable urine samples to be collected.  All that is necessary is to dip a urine test strip in the sample and after a specified time read the result.

Does urine glucose have to be tested every day?

At the beginning of insulin therapy at least daily monitoring of urine glucose is needed.  We will advise regarding this once the optimal insulin dosage has been determined and diet and exercise have been stabilised.  Once stabilised urine testing may only be necessary once or twice a week.

How will I know if my pet is on the correct dose of insulin?

Monitoring appetite, water consumption, urine output and energy levels are probably just as important as urine tests.  With cats in particular, obtaining a urine sample can present problems.  Many owners depend upon careful monitoring of fluid intake combined with changes in demeanour.  It is imperative that if you notice any increase in thirst, however slight, let us know without delay.

Are there any other tests that will be necessary?

Serum biochemistry tests involve the evaluation of glucose levels and tests for liver and kidney function.  Results can range from mild elevation of liver enzymes due to dehydration (as a result of the previously undetected diabetes) to more severe liver damage due to alterations in fat metabolism.  This may also be reflected in elevated serum cholesterol levels which is also included in the serum biochemistry test.

Will these tests have to be repeated for the rest of my pet's life?

At present, treatment for diabetes involves stabilising but not curing the patient.  Daily injections of insulin are usually required for the rest of the pet's life, although sometimes spontaneous recovery can occur.  Once exercise levels, food and insulin dosage have all been stabilised it is prudent to have regular check-ups (including laboratory tests) to ensure that everything is proceeding according to plan.