In this VETgirl online veterinary continuing education blog sponsored by Purina® Pro Plan® Veterinary Diets, Dr. Chen Gilor, DACVIM, Associate Professor at University of Florida reviews diabetes mellitus in cats. Can we improve the odds of cats avoiding diabetes? Please note the opinions in this blog are the expressed opinion of the author and not directly endorsed by VETgirl.
Will This Cat Become Diabetic? Improving the Odds Requires a Proactive Approach
By Chen Gilor, DVM, PhD, DACVIM (SAIM), Associate Professor, Small Animal Internal Medicine, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida
If you had a crystal ball to tell you a feline patient was likely to develop diabetes, what would you do differently? Chances are, you would implement some simple but effective strategies to help that cat. Insulin therapy can be dangerous and stressful for the pet and expensive and burdensome for the owner. If we want to do right by our patients, we should strive to find ways to avert or delay the onset of diabetes, manage patients if it does start and help cats achieve remission if we can.
Diabetes? Prediabetes? Subclinical diabetes?
We currently don’t have a crystal ball—nor prospective longitudinal studies—to identify which feline patients will develop diabetes. However, we can look at the human model for Type 2 diabetes and draw parallels. Not every overweight person becomes diabetic, nor does every overweight cat, but we know that being obese or overweight over time is correlated with developing the disease. This provides a talking point for both physicians and veterinarians. When we see an overweight patient, we can explain that the risk of developing diabetes is increased. While the [human] patient or cat owner might not respond to a general recommendation for weight loss, they might take positive action if provided a specific recommendation such as “You are/your cat is at high risk of becoming diabetic if you/they don’t lose XX pounds.”
Humans are considered to have prediabetes when their fasting blood glucose level is between 100 and 125, or when they fail a glucose oral tolerance test.1 Prediabetes is also diagnosed in patients with increased hemoglobin A1C (5.7-6.4%).1 The higher the A1C, the greater the risk. The good news for these individuals is that it is not too late to implement changes that can change the trajectory of disease development. Patients can lose weight, switch to a low-carbohydrate diet and possibly take certain medications in an attempt to reverse the situation. While we don’t have definitive proof that the paradigm is the same in cats, it makes practical sense to assume the pattern is similar.
Not to be confused with prediabetes is the term subclinical diabetes. This describes the cat that has elevated glucose and/or glycated protein (fructosamine or hemoglobin A1C) readings that are consistent with diabetes but has not yet developed clinical signs of diabetes. In such cases, it’s important to look beyond the lack of clinical signs of disease: Treatment in this stage might increase the likelihood of diabetic remission later on.
Can we “catch” cats early?
In veterinary medicine, we have no definition for prediabetes in cats. We don’t know exactly what initiates the condition or causes it to progress. However, because we know that diabetes is triggered by beta cell dysfunction and loss, we can take steps to preserve beta cells in cats we believe to be at risk.
The challenge is that interpreting test results can be difficult. A mild elevation of blood glucose can be easily dismissed as stress because the office visit alone can cause a temporary rise in glucose. On the flip side, the cat does not have to have a markedly high blood glucose reading to have diabetes. A reading of between 140 and 160 should prompt the practitioner to investigate further. Even so, testing the fructosamine level may not provide the answer they’re looking for because the test is not sensitive enough. We recently completed a study to assess the reference range of hemoglobin A1C in cats and how it’s affected by anemia. Based on this study’s results, I would consider running a hemoglobin A1C test in cases like these to provide more information.
Formulate a plan of action
Once identified, what should be done with the “at risk” cat—for instance, the overweight cat that is not overtly diabetic and in need of exogenous insulin, but whose screening tests indicate the potential for disease development? A practical and proactive approach includes the following steps:
• Monitor the patient. Regular monitoring of cats for changes in blood glucose and other parameters can ensure that significant changes are detected early. As noted above, there can be challenges to interpreting results, but the important point is to be proactive. When I see high blood glucose readings—especially with an obese cat—that’s my cue to run a hemoglobin A1C test to tell me more.
• Reduce body weight. Optimizing body weight is an important step that can help decrease insulin resistance. This can be achieved with nutritional management and, if necessary, medication to help achieve weight loss. While medication use can be expensive, it is a safe and effective strategy. I tell clients that if weight loss can help prevent the cat from becoming diabetic, it is worth it.
• Recommend a low-carbohydrate diet. If the cat is not already on a therapeutic low-carbohydrate diet, such as one of the canned Purina® Pro Plan® Veterinary Diets DM Dietetic Management® Feline Formulas, they should start. Reducing carbohydrate reduces the amount of insulin required to maintain normal blood glucose. Low-carbohydrate therapeutic diets such as these are also high in protein to help maintain lean body mass and ideal body condition. This is important as the cat loses weight.
• Preserve beta cell function and avert its further loss. This is currently the most challenging step. Aggressive management of hyperglycemia and hyperlipidemia might help reduce beta cell glucolipotoxicity. Drugs in the GLP-1 receptor agonist family, such as injectable exenatide, likely help in beta cell preservation. This drug has also been studied in cats, with similar effects to those noted in people and other models of diabetes.
In addition to being proactive measures for the practitioner to take in high-risk cats, the latter three steps are also key to achieving remission in diabetic cats.
By identifying at-risk patients early, we can counsel owners about dietary changes, weight loss and other strategies that may help their cats avoid or delay the need for insulin administration. This, in turn, can help cats—and their owners—maintain an optimal quality of life.
1. Centers for Disease Control and Prevention (CDC) Diabetes Tests. https://www.cdc.gov/diabetes/basics/getting-tested.html#:~:text=Fasting%20Blood%20Sugar%20Test&text=A%20fasting%20blood%20sugar%20level,higher%20indicates%20you%20have%20diabetes. Webpage accessed February 23, 2022.