• Most diabetic cats have diabetes mellitus type 2, meaning the body’s cells develop a “resistance” to insulin; sometimes the body fails to make enough insulin to serve its needs (diabetes mellitus type 1).
  • After treatment for diabetes is started, periodic blood and urine testing may be recommended to help ensure that the current treatment (including insulin dosage) is adequate.
  • Many cats live active, happy lives once their diabetes is well regulated. Some cats go into “remission” and no longer require insulin, whereas other cats need insulin for the rest of their lives.

What Is Diabetes?

Diabetes mellitus is an illness caused by the body’s inability to either make or use insulin, which is a hormone produced and released by specialized cells in the pancreas. Insulin permits the body’s cells to take sugar (glucose) from the blood and use it for their metabolism and other functions. Diabetes mellitus develops when the pancreas doesn’t make enough insulin or when the body’s cells are unable to use available insulin to take glucose from the blood.

Type 1 diabetes (referred to as “insulin dependent” diabetes) occurs when the pancreas doesn’t make enough insulin. Type 2 diabetes, also referred to as “relative insulin deficiency,” occurs when the body’s cells develop “insulin resistance,” meaning that they are unable to effectively use available insulin, or when the pancreas is producing some insulin, but not enough to serve the body’s needs. Most diabetic cats have type 2 diabetes. However, many of them still require insulin for adequate control of their illness.

What Are the Clinical Signs of Diabetes in Cats?

Diabetes can exist for a while before it begins to make an animal obviously ill. Clinical signs may vary depending on the stage of disease, but they can include the following:

  • Increased drinking and urination
  • Urinating outside of the litterbox
  • Weight loss
  • Vomiting
  • Dehydration
  • Lethargy (tiredness)
  • Increase or decrease in appetite

How Is Diabetes Diagnosed?

Your veterinarian may suspect that your cat has diabetes if any suspicious clinical signs, such as increased drinking, have been observed at home. After performing a thorough physical examination, your veterinarian may recommend some of these tests to help confirm a diagnosis:

  • CBC (complete blood count) and chemistry profile: When a pet is ill, these tests are commonly performed together during initial blood testing to provide information about the pet’s organ systems. The CBC and chemistry profile may show dehydration, an elevated blood sugar level, or other changes that can occur with diabetes.
  • Urinalysis: Evaluation of a urine sample may show the presence of sugar (glucose) in the urine if a cat has diabetes.
  • Fructosamine: Fructosamine is a protein in the blood that binds very securely to glucose. The fructosamine level is therefore a close estimation of the blood glucose level, but it is less likely to change due to stress and other factors that change the blood glucose level. Additionally, the fructosamine level indicates where the blood sugar levels have been during the previous 2 to 3 weeks. In a cat with diabetes, the blood sugar levels are likely high for long periods of time, which would be reflected by an increased fructosamine level.

How Is Diabetes Treated?

Because many cats have type 2 diabetes, insulin injections may not be required in all cases. Your veterinarian may first recommend dietary changes, weight loss and/or medication to control your cat’s diabetes. If this therapy is not successful, insulin injections are generally recommended to control the condition.

It is very helpful to write a medication schedule for your cat on the calendar, including the date and time that any medications, including insulin, need to be administered to maintain accurate records. This will help you avoid forgetting to give a dose of insulin to your cat and aid in tracking your cat’s treatment.

After treatment begins, periodic blood and urine tests are generally recommended. This helps ensure that the current treatment (including insulin dosage) is right for your cat. Your cat’s weight, appetite, drinking and urination, and attitude at home can all provide useful information that helps determine if diabetes is being well managed. Your veterinarian will consider all of these factors when making recommendations for continued management.

Many cats live active, happy lives once their diabetes is well regulated. Some cats even go into “remission,” meaning that they no longer require insulin. For other cats, insulin therapy must continue for the rest of their life.

Can Diabetes Be Prevented?

Certain medical conditions, such as being overweight or obese, can lead to insulin resistance and increase the risk of a cat developing diabetes. Keeping your cat’s weight within a healthy range can reduce the risk of diabetes. However, not all cases of diabetes are preventable. Scheduling regular checkups and wellness screening with your veterinarian can increase the chances of diagnosing diabetes early and initiating treatment as soon as possible.

Ask your veterinarian what steps you can take to keep your cat healthy and reduce the risk of diabetes


  • Blood glucose and fructosamine tests are helpful tools for monitoringdiabetic patients.
  • The results of glucose and fructosamine testing can helpyour veterinarian ensure that your pet’s diabetes is being adequately managed.
  • Only small amounts of blood are required to perform these tests.

What Are Glucose Testing and Fructosamine Testing?

In diabetic patients, spot-checking the blood glucose (or blood sugar) is a quick and direct way to tell what the level is. The rapid result permits quick detection and management of a dangerously low or an extremely high level. However, blood glucose testing provides only a “snapshot” of the total blood glucose “picture.” The test result does not indicate what the blood glucose level will be 2 hours later, 8 hours later, or the next day. Your veterinarian needs to do other testing to obtain this information.

Performing a blood glucose curve can provide some of the missing information. A blood glucose curve involves repeatedly measuring the blood glucose level every 1 to 2 hours over a period of time—usually 12 to 24 hours. Like a regular blood glucose measurement, a blood glucose curve also directly measures the blood sugar, but (compared with a single blood glucose reading) it tells your veterinarian more information about how the blood glucose level may be changing over time.

Fructosamine testing involves checking the fructosamine level in the blood, and this testing is another way to monitor diabetic pets. Fructosamine is a protein thatbinds very strongly to glucose in the blood. Because fructosamine occurs in proportion to blood glucose, it can provide an accurate estimate of the amount of glucose in the blood. When the fructosamine level is measured, it helps determine the average glucose level for the previous 2 to 3 weeks. Fructosamine monitoring is often the preferred method for monitoring the glucose level in cats because it is not affected by stress, which can cause asharp increase in the blood glucose levelin cats. Your veterinarian may recommend using fructosamine level monitoring alone or in combination with blood glucose testing, glucose curve monitoring, and other tools to help monitor your diabetic pet.

How Are Glucose Testing and Fructosamine Testing Performed?

Spot-checking your pet’s blood glucose level takes only a few minutes and requires only a small amount of blood. Your veterinary team will likely ask you when your pet’s most recent meal was eaten and when the most recent insulin injection was given because these variables can affect the blood glucose reading. Blood glucose spot-testing is generally done during an outpatient visit.

Blood glucose curves require a brief stay in the hospital. Your veterinary team will generally ask about your pet’s feeding and insulin schedule so the same schedule (or one as close as possible) can be continued while your pet is undergoing the blood glucose curve. During the blood glucose curve, blood is drawn every 1 to 2 hours, and the blood glucose level is measured and recorded. The resulting chart or table shows how the blood glucose level has changed during the measuring period. Some veterinarians perform a curve for 8 to 12 hours, and some prefer 24-hour curves. During this time, your veterinary team will try to keep your pet’s stress and anxiety to a minimum, as stress can affect the blood glucose level in some patients, especially cats.

Fructosamine testing is generally done during an outpatient visit and requires a small blood sample that is submitted to a laboratory for analysis. Drawing blood generally takes only a few seconds, and the test result is usually available within a few days. The analysis measures the amount of fructosamine in the blood sample. The test results indicate whether the patient has excellent, good, fair, or poor glucose control.

What Are the Benefits of Glucose and Fructosamine Testing?

Diabetes is a complicated illness, and there are many approaches to managing diabetes in pets. Whether your veterinarian prefers to use blood glucose spot-testing, a glucose curve, fructosamine testing, or a combination of these, he or she will consider these results along with other valuable information, such as appetite consistency, weight gain or loss, and frequency of drinking and urination, to determine if your pet’s diabetes is being well managed. If your pet is receiving insulin, this information will help your veterinarian determine if the insulin dosage is acceptable or if an adjustment should be made. Your veterinarian will also discuss with you how often monitoring tests should be repeated. Your veterinarian may recommend additional testing (such as urine testing) to see how well your pet is responding to diabetes management.