Section 10: Troubleshooting in Diabetic Cats

Managing diabetic cats is not always straightforward. The approach to troubleshooting problems with diabetic management differs between patients who receive SGLT2 inhibitors and those treated with insulin.

When using a CGM to monitor either SGLT2 inhibitor or insulin use, if persistent moderate hyperglycemia is seen in a cat who is otherwise not showing clinical signs and maintaining or gaining weight, therapy adjustment may not be necessary. Task force members have frequently managed clinically well cats with glucose concentrations persistently >250 mg/dL as determined by CGM.

Troubleshooting SGLT2 Inhibitor Treatment

Clinical hypoglycemia is not a concern with SGLT2 inhibitor treatment, and unresponsive hyperglycemia is uncommon. If hyperglycemia persists, ensure that the cat is receiving the prescribed dose. If clients are mixing the drug with food, they should avoid mixing the dose with a full meal as cats may be under-dosed if not all food is consumed. If hyperglycemia remains despite accurate dosing and administration, discontinue the SGLT2 inhibitor and transition to insulin. Persistent biochemical changes such as hypercalcemia or severe hyperlipidemia may also require discontinuing the SGLT2 inhibitor and transitioning to insulin. Although perineal mycotic infections are routinely reported in human patients treated with SGLT2 inhibitors, these infections have not been described in feline patients.

One of the most common complications with SGLT2 inhibitors is diarrhea. This can be managed with symptomatic care or a 3- to 5-day 25-50% reduction in dose, as it tends to be transient in most cases. In some instances, it may help to discontinue the SGLT2 inhibitor for 2–3 days and allow the diarrhea to improve, then restart treatment at half the dose and gradually increase it to the prescribed dose. Changing to another SGLT2 inhibitor may be helpful in some cats. For persistent diarrhea, antibiotics are not indicated, and the patient may require transition to insulin.

Troubleshooting Insulin Treatment
(See Also Figure 15.2)

Problematic patients who are receiving insulin usually fall into two categories: cats who become hypoglycemic and cats who exhibit persistent hyperglycemia.

Always confirm that insulin is being handled and administered correctly. Check the dose on the syringe and injection routine with the client and ensure that doses are not skipped or accidentally administered more than once. Credentialed technicians can perform initial consultations to gather this information and provide additional client education (see Box, Technician Initial Consultations).

Hypoglycemia may occur with excessive insulin administration, waxing and waning IR conditions, or with unrecognized diabetic remission, and can be life threatening (Figure 15.1, Managing Hypoglycemia). It is important for caregivers, including hospital staff, to know the clinical signs of and risks for hypoglycemia (see Section 11, Client Education). If a cat becomes hypoglycemic, investigate insulin administration, appetite or vomiting, and general health over the previous days to weeks. Diet changes, intestinal disease, and pancreatitis are just a few reasons a cat may eat less and become at risk for hypoglycemia if the same dose of insulin is administered.

Persistent hyperglycemia despite increasing doses of insulin may be due to IR, but proper insulin care and administration should always be confirmed first. Once confirmed, consider any concurrently administered medications. Discontinue insulin-resistance causing medication(s) if possible, and if still uncontrolled 2 wk after discontinuation, increase insulin dose.

Multiple diseases and conditions can complicate diabetic regulation with insulin by inducing IR, including dental disease, bacterial infections, pancreatitis, inflammatory bowel disease, and hypersomatotropism (acromegaly). Second-level diagnostics, including gastrointestinal testing (fPLI, trypsin-like immunoreactivity, cobalamin, folate), abdominal ultrasound, and hormonal testing, may be appropriate.^1,2 Note that unregulated hyperthyroidism may cause a decrease in insulin-like growth factor (IGF-1),³ and IGF-1 may be increased in obese cats.⁴ IGF-1 testing should be done at least 4–6 wk after starting insulin in newly diabetic cats, as they have significantly lower IGF-1 levels before starting insulin administration.⁵ Resolution of concurrent diseases may eliminate the need for an increased insulin dose and, in some cases, may reduce or eliminate the need for insulin administration altogether.

Credentialed Technician Consultations for Troubleshooting Insulin Therapy

• Ask about current food (type, amount, timing), any dietary changes, and any new medications, supplements, or clinical signs suggestive of insulin resistance.
• Ask the client how they store and prepare the insulin (i.e., shaking versus rolling).
• Ensure that the syringes match the insulin concentration (U-100 versus U-40).
• If using an insulin pen, ask the client whether they prime needles before each use.
• Assess how long the insulin vial has been in use since being opened or uncapped; consider replacement if in use more than 4 mo.
• Using sterile saline, have the client demonstrate how they administer injections to their cat.
• Have the client keep a log that family members initial when they administer the insulin to ensure doses are not skipped or doubled.

If no underlying disease is identified and the patient is not regulated, consider changing to another type of insulin. When changing insulins, it is safest to initiate the new type at a standard starting dose, such as 1 unit/cat twice daily for glargine U-100 or PZI. Consult with a specialist if the patient still cannot be regulated. Diabetic ketoacidosis is a serious and potentially fatal complication of diabetes, whether on insulin or SGLT2 inhibitors (see Section 12, Diabetic Ketoacidosis).

The 2026 AAHA Diabetes Management Guidelines for Cats are generously supported by Adapet Medical, Boehringer Ingelheim, Dechra, and Merck Animal Health.