Normal Blood Glucose Ranges for Cats

By Betty Lewis

Maintaining a proper blood glucose level can be tricky business, as even a healthy cat's glucose level changes throughout the day. If the vet detects a higher than normal blood glucose level in your cat, she'll require a few more tests to determine the cause. If she has diabetes, you and your vet will have to work together to ensure her glucose level remains in a normal range throughout the day.

Normal Blood Glucose Range

According to The Cat Practice in Birmingham, Michigan, the normal blood glucose range for a cat is between 75 and 159 mg/dL, though the number may climb higher if the cat is stressed or frightened. Blood glucose levels are ruled by insulin, the hormone produced by the pancreas. If your cat's pancreas isn't producing sufficient insulin, her glucose levels rise. In addition to stress, pancreatitis, diet and infection also can cause higher than normal glucose readings; if your vet detects a high level, he'll conduct other tests to gain a more clear picture.

Testing for Diabetes

The vet will first consider if your cat's showing symptoms of diabetes, including weight gain or loss and increased thirst, urination and appetite. Since the stress of the vet visit can cause her glucose level to spike, he'll want to determine that the high level isn't a stress reaction. A complete blood count as well as a blood chemistry profile will help the vet to determine if there are other potential illnesses present that could cause an elevated glucose level. An urinalysis also is helpful because when a cat's glucose level is higher than 240 mg/dL, sugar is present in the urine. As well, urine may contain other hints of diabetes, including pus, bacteria and high numbers of ketone bodies. Tests, symptoms and medical history will help confirm a diagnosis of diabetes, as well as whether it's related to an underlying condition.

Insulin Management

If there's something at work causing the increased glucose level, treatment will address the root cause of the hyperglycemia. If the diagnosis is diabetes, your cat likely will need regular insulin injections to manage her glucose level. Since a fluctuation in blood glucose levels can have a significant impact on your cat's health quickly, it's critical to follow the vet's directions. Even when you follow the instructions, chances are your cat's insulin needs will change over time as her body changes. That means you'll need to stay in regular contact with your vet to ensure she's getting the proper amount of insulin. You may work with your vet to do this at home with a handheld glucose meter, or you may rely on the vet to do the testing with a glucose curve.

Glucose Curve

A glucose curve helps the vet to ensure your cat is receiving the correct insulin dose by tracking how her blood glucose level responds through the day. After the cat has her morning meal, an initial blood draw is taken just before her morning insulin injection. Blood samples are collected every two hours throughout the day for 12 hours. The glucose levels are plotted to generate a curve and the vet determines how, or if, to adjust her insulin injections. Ultimately, the vet strives to build a dosing schedule that will keep her glucose level between 120 and 300 mg/dL throughout the day. Glucose curves are performed between every two and four months after the cat is stabilized.

Fructosamine Test

While the glucose curve is a snapshot of half a day, a fructosamine test can give an idea of where the glucose levels are over the period of a couple of weeks. Fructosamine is a compound that forms when certain blood proteins and blood sugar come together. A stable compound that forms slowly, its presence indicates consistently high blood sugar.

Home Checks

Paying attention to your cat's behavior will give you a good idea of how she's doing -- changes in her energy, food and water intake and urinary habits are indicators that she may need some adjustments to her insulin. A urine test strip also will tell the tale; when you're ready to dip her strip, switch her litter box for a clean box lined with nonabsorbing plastic pellets instead of standard absorbing kitty litter. Strips change color depending on the presence of glucose in the urine. Your vet will guide you on how to interpret the results and their impact on the insulin dosage.