When we manage a diabetic animal, we are administering insulin in order to bring the blood sugar down, hopefully into the normal range. Too much insulin can drive the glucose too low, causing hypoglycemia. If the blood sugar goes too low, the pet may experience weakness, disorientation and even seizures or coma. During the initial phases of getting diabetes under control with insulin, we like to have owners use a simple urine dipstick test to help monitor the effectiveness of our therapy.

Urine glucose testing is based on the fact that excessive amounts of glucose in the blood will be filtered by the kidneys into the urine. Once the amount of glucose in the blood exceeds the renal threshold (180 mg/dL) , glucose is spilled into the urine. The renal threshold is the level at the kidneys can not “process” any more blood glucose and it spills into the urine. If the blood glucose is high for an extended period of time, glucose is usually present in the urine. The amount of glucose present in the urine depends on how high the blood glucose was, and how long the blood glucose was high.

Therefore we can get a general feeling for how well the blood sugar has been controlled based on how much glucose is in the urine. In general, we always want to have a small amount of glucose in the urine of our diabetic pets, because if there is no glucose in the urine, we do not know just how low the blood sugar has been. So if we test a dog with uncontrolled diabetes, we might find a urine sugar of 2000 mg/dl on the urine dipstick.

When we start insulin therapy, we would expect the glucose level to go down over the first few days. However, if the urine glucose level goes NEGATIVE, all we know is that the blood sugar is less than 180mg/dl. It could mean that the blood sugar was 160 or it could just as easily be 20mg/dl. You can see that there is a high risk that if the urine glucose is negative that your pet may have been experiencing hypoglycemia for some part of the day.

How to use Urine Glucose Dipsticks

Urine glucose test strips like the pictures shown below are used. The test strip has a little test area at the end that is dipped into urine or held in the urine stream. After a certain amount of time, the color of the test area is compared to a reference color chart. Bayer makes several types of urine tests strips. Diastix and Clinistix test only for urine glucose. Keto-Diastix test for both glucose and ketones. The Diastix have more “levels” of glucose measurement than the Clinistix. Follow the instructions that come with your test strips, and use the reference color chart on the bottle or box. The picture shown below is just an example – the colors are NOT to be used to compare your urine test strip.

The color chart tells you approximately how much glucose has spilled into your pet’s urine.

Note: Different test strip brands use different numbers to indicate the amount of glucose in the urine. When talking to your vet, it is important that you are both thinking of the same value. For example a “1” on one brand of strips may indicate very high urine glucose, while on another strip a “1” is a low urine glucose. A “trace” amount usually refers to the first non-negative color patch.

Here is a chart comparing the results you can obtain from Diastix, Keto-diastix, and Clinistix.

Diastix
glucose
(%) Negative 1/10 1/4 1/2 1 2
(mg/dL) Negative 100 250 500 1000 2000
or more
Keto-Diastix
Ketone
(mg/dL) Negative 5 15 40 80 160
Clinistix
glucose
no units Negative
(pink)
Light
(reddish)
Medium
(maroon)
Dark
(purple)
might be
referred to as:
negative 1 2 3

Accuracy

Urine glucose testing is not necessarily an accurate way of measuring blood glucose, because some animals may hold their urine for a long time and the amount of glucose in the urine would only reflect an average level over that period of time. Pets that urinate more frequently will have a more accurate reflection of the blood glucose based on their urine glucose.

What does our veterinary clinic use the strips for?

Our veterinarians use the dipsticks to help us prevent hypoglycemia. If your pet has two negative urine glucose tests in a row, we will probably reduce the amount of insulin because the blood sugar has remained below 180mg/dl during the entire time the urine was collecting. This is particularly important during the first few months of insulin therapy because some pets will become hypoglycemic on standard doses of insulin.

If you use the Keto-diastix, we can also get a good idea when the body is very poorly regulated. Ketones are chemicals which are formed when the body cannot use glucose for energy. If we see ketones in the urine, it means that we are not controlling the blood sugar accurately and more important, these pets are likely to become very sick.

Our veterinarians do not generally use dipsticks to tell us when to increase insulin. Instead we rely on blood glucose tests and fructosamine tests to make these decisions.