New oral diabetes medication for cats requires careful case selection

Emily Singler, VMD - 1/13/2023

Last month, the Food and Drug Administration (FDA) announced the approval of Bexacat, the first oral drug for treatment of diabetes in cats. Bexagliflozin, the drug in Bexacat, is a sodium-glucose cotransporter 2 inhibitor that prevents renal glucose reabsorption, thereby causing excess blood glucose to be excreted in the urine.

It is labeled for use in otherwise healthy cats with diabetes mellitus who have not previously been treated with insulin. Given as a tablet that can be crushed and mixed into food once daily, it carries a much lower risk of dangerous hypoglycemia when compared to insulin administration.

Not all diabetic cats will be good candidates to use this medication, however, and on January 13, the FDA released a letter to veterinarians issuing an advisory about important safety considerations for the use of this drug.

The intricacies of diabetes in cats

Renee Rucinsky, DVM, DABVP(F), president-elect of the American Board of Veterinary Practitioners, provides some insight on the appropriate use of Bexacat. She points out that many cat owners may be afraid to give insulin injections to their cats. Cost can also be a factor, especially as the price of insulin has skyrocketed. Other obstacles to electing insulin treatment for cat owners include correct dosing, staying on schedule, and the potential for life-threatening hypoglycemia.

Veterinarians and veterinary teams face challenges too—including finding adequate time to properly educate cat owners, and carefully considering the intricacies of diabetes in cats, a factor that makes every case very different.

For these reasons, the idea of a once-daily oral medication that does not carry as much risk of hypoglycemia can be very appealing. Appropriate case selection, however, is “imperative,” Rucinsky cautions.

Benefits of Bexacat

While cats and dogs cannot strictly be categorized as insulin dependent or insulin resistant, Rucinsky indicates that diabetic cats are more likely to be insulin resistant. For these cats, providing exogenous insulin may not be necessary or helpful. Bexacat will work to improve glycemic control without providing additional insulin. Field studies using Bexacat showed that the drug was more than 80% effective in improving glycemic control in diabetic cats.

Bexagliflozin has also been studied and is currently being developed for treatment of type 2 diabetes in humans. Clinical trials have reported not only improved glycemic control, but also improved weight loss and a decrease in hypertension in type 2 diabetics. Nondiabetic patients with chronic kidney disease and certain types of heart failure have also experienced health benefits when taking bexagliflozin. While weight loss is a potential benefit of this drug in humans, the client information sheet for Bexacat lists weight gain as a possible effect of treatment in cats. No cause is given for weight gain in cats, but it may be gaining back weight that was lost before their diabetes was well controlled.

When insulin is the safer choice

When deciding whether to use this drug for a patient, Elanco (the manufacturer) lists warnings that must be carefully considered. Bexacat is only appropriate for use in cats diagnosed with diabetes mellitus who are showing no other signs of being sick and who have never received insulin treatment.

Rucinsky explains that this is very important, as cats can still develop diabetic ketoacidosis (DKA), a potentially fatal complication, while taking Bexacat. If a cat is sick at the time of diagnosis, they may be at higher risk for developing DKA, and insulin is a “much safer choice,” Rucinsky advises.

Signs to avoid Bexacat

Signs of illness that would warrant avoiding the use of Bexacat include any evidence of “other active systemic disease including renal, hepatic, or pancreatic disease, or current DKA” as well as:

Dehydration
Lethargy
Anorexia
Weakness
Difficulty walking or standing

Who should not get Bexacat

Newly diagnosed geriatric diabetic cats, roughly 13 years old or older—and especially those who were not overweight prior to diagnosis—may be more likely to be insulin dependent and to have comorbidities, Rucinsky explains. For this reason, they are likely not good candidates for treatment with Bexacat.

Cats who have already been treated with insulin are not candidates to take this drug either. “In these cats,” Rucinsky explains, “withdrawal of insulin therapy may lead to DKA because the cat may not be able to produce enough endogenous insulin.”

The danger when looking for signs of DKA in cats on Bexacat is that they may have euglycemic DKA, which can make it harder to diagnose and treat. “It’s potentially going to be unfamiliar territory treating this problem, and veterinary teams will have to be ready to learn the nuances of treating potentially really sick cats whose lab results don’t look like what they are typically used to seeing.”

How should Bexacat be used?

Both Rucinsky and Elanco point out that there is no way to know ahead of time which cats are insulin resistant and which ones are insulin dependent. The best way to select good candidates for Bexacat is to look carefully for any signs of illness, evaluate each cat’s history for any previous use of insulin, and advise the owners of the risks.

Rucinsky advises that cats who have newly been diagnosed with diabetes are more likely to still be able to produce enough insulin to prevent DKA. Even so, all cats started on Bexacat should have their serum Beta-Hydroxybutyrate (BHB) levels checked 3 to 5 days after starting therapy using an in-house ketone meter. If levels are elevated, DKA may be more likely.

Furthermore, cats should be monitored closely for any clinical signs that may indicate they are developing DKA, even if their blood sugar remains within normal limits. Cats who develop signs of DKA or any other illness should stop taking Bexacat immediately, per Elanco, and seek veterinary treatment.

Even though she is cautious about case selection, Rucinsky is excited about Bexacat and the benefits it can provide to cats and their owners. Hopefully this drug, along with careful patient evaluation and client education, will open the doors to treatment for cats who otherwise might not receive any.

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