When a cat is diagnosed with diabetes, insulin administration is a key component of their treatment plan. Cats who are being treated with insulin should have their blood sugar levels monitored closely to avoid blood sugar levels that are too high or too low.  

Some cats may be candidates for a needle-free alternative to insulin, such as Bexacat (bexagliflozin). Bexacat is a once-daily flavored tablet for treating diabetes. Cats taking Bexacat also must have their blood sugar levels regularly monitored by their veterinarian. 

Veterinarians use what’s called a fructosamine test for cats and continuous glucose monitoring to adjust the dose of insulin in order to best control the cat’s blood sugar and minimize the signs of diabetes. A fructosamine test can also be used to see how cats are responding to an insulin alternative such as Bexacat. This helps determine whether cats can continue using the medication or need to switch to insulin.

In this article, you will learn what these diabetic blood tests are, how they work, and what you can expect when it comes to monitoring blood sugar levels in diabetic cats as part of treatment.

What Is a Fructosamine Test for Cats?

Serum fructosamine testing is used by veterinarians to evaluate how well a diabetic cat is responding to insulin therapy or insulin alternatives over the long term. 

Fructosamine is a protein found in blood serum that has sugar attached to it. The level of fructosamine in blood serum samples is representative of the average blood sugar levels that a cat has had over the past 1-2 weeks. If it is too high, then that lets the veterinarian know that they need to adjust the cat’s insulin dosage or type of medication, their food, or look for something else that is causing problems with the cat’s blood sugar.

In contrast to a blood glucose curve for cats, only one blood draw is required to obtain a blood sample for the fructosamine test. The fructosamine test is either run in house at the veterinary clinic or the blood sample is sent to a local laboratory for analysis.

Also unlike a glucose curve in cats, fructosamine tests do not require any special timing or fasting. However, serum fructosamine cannot detect abrupt changes in blood sugar, only long-term changes. Therefore, it is important to still monitor your cat daily at home for any signs of abnormal blood sugar levels like drinking and peeing more, and call your veterinarian immediately if you see them, even if your cat has normal fructosamine levels when they are tested.

Fructosamine Test vs. Glucose Curve in Cats

Monitoring blood sugar in cats who have been diagnosed with diabetes can be tricky. A glucose curve in cats, which is the standard blood test used for diabetics, isn’t always a reliable test for our feline companions. That’s because when cats are stressed by the veterinary hospital or by having their blood drawn, their blood sugar is higher than it would be at home when they are calm. 

A fructosamine test for cats is unaffected by stress, which can make it a good test for cats who have elevated blood sugar due to stress. This is why veterinarians use a fructosamine blood test to check blood sugar control in diabetic cats.

A fructosamine test requires a veterinary professional trained to draw blood samples from a cat — it cannot be done by a pet parent. It is typically done in a veterinary hospital, but it can also be done by a veterinary professional who comes to your home for a house call.

How often your cat needs a fructosamine test depends on how well your cat’s diabetes is controlled. If your cat’s diabetes is well controlled, then you will likely only need a fructosamine test every 6 months. If your cat’s diabetes is not controlled, then your cat may need a fructosamine blood test every few weeks until their diabetes is under control.

Continuous Glucose Monitoring for Cats

Continuous glucose monitors (CGM) are being used more and more in veterinary medicine as an alternative way to monitor diabetic cats at home. CGM provides continual data about your cat’s blood sugar, and is a good option if your cat’s diabetes is difficult to control, your cat is newly diagnosed with diabetes, or for cats that may be approaching diabetic remission (cure). In general, if your cat is a stable diabetic that only needs blood tests every six months, then testing them with serum fructosamine is a better choice than CGM.

The FreeStyle Libre system is the most common CGM technology that is utilized in cats. It uses a small sensor disc that is placed on an area of skin (usually the neck or thorax) that has been shaved. The sensor disc communicates with a phone app or a reader device that stores data from the disc. Collected data can also be sent to your veterinarian for analysis. CGM measures interstitial glucose, which while it is different from blood glucose, still correlates fairly closely and can be used to monitor diabetic cats. 

CGM is generally well tolerated in most cats. It is easy to place, avoids multiple needle pokes, and lasts about 2 weeks in most patients. In addition, the FreeStyle device has an alarm that will alert you if glucose levels are too high or too low.

Fructosamine Test Process: What to Expect

Fortunately, if your cat needs a fructosamine test, it is a fairly easy, quick, and straightforward outpatient procedure. Sometimes, if your cat doesn’t need an examination by a veterinarian, you may only need a veterinary technician to draw your cat’s blood and submit the sample, which can save you time and money.

For well-controlled diabetic cats, it should only take 15-20 minutes to have your cat’s blood drawn at the veterinary hospital or in your home. If your cat’s diabetes isn’t controlled, then you may need to see the veterinarian and have your cat’s blood drawn, which will take longer — between 45 minutes to an hour —and will require additional cost.

There are no restrictions after your cat’s blood is drawn for a fructosamine test — they can go back to their normal routine afterward. If there is a pressure bandage placed on their arm where blood is drawn, you will need to remove it after 15 minutes.

If your veterinary clinic runs the tests in house, then they will likely call you later the same day with results and recommendations. If they have to send the blood sample to the local laboratory, then it will be a day or two before they call you with the results.

If you don’t hear from your veterinary clinic within two days, call them and ask for an update.

Cost of Fructosamine Test for Cats

While the cost of a fructosamine test can vary by geographical location, the average cost of the test ranges from $75-$125. If your cat requires an examination by a veterinarian at the same time as a test, that is an additional cost.

What The Results Mean

If your cat is taking insulin, here is what you can expect. If your cat’s fructosamine test comes back normal and your cat doesn’t have any signs of high blood sugar at home, then your veterinarian will likely recommend that you don’t change anything about your cat’s routine. They’ll likely ask you to come back in 6 months to repeat the test.

If your cat’s fructosamine test comes back too high, then your veterinarian will likely increase your cat’s insulin dosage, recommend that you switch foods, or both. If your cat’s fructosamine test comes back too low, then your veterinarian will reduce the insulin dosage. In either case, you will likely be asked to authorize your cat to be retested in 3-4 weeks to check if those changes help regulate your cat’s blood sugar, which is the end goal.

If your cat is prescribed Bexacat, recommended monitoring includes glucose curves and fructosamine tests at 2, 4, and 8 weeks after starting treatment (1). If these tests show that your cat’s average blood glucose is too high, they will need to stop taking Bexacat and transition to insulin. If your cat is responding well to Bexacat treatment after 8 weeks, they will be re-checked every 3 months (or as medically indicated).

Reference

1. Bexacat Patient Selection and Monitoring for Diabetic Cats. Jan 2023. Retrieved from https://assets.elanco.com/0cec44ed-3eaa-0009-2029-666567e7e4de/1b0d2a58-023b-4ce1-948e-4f0f011c0eed/Bexacat%20Vet%20Patient%20Selection-Monitoring%20Sheet%20-%202nd%20update%20-%20Jan%202023.pdf