Stress Hyperglycaemia in Cats: Why One High Reading Isn't Always Diabetes

Quick answer

A vet visit can raise a cat's blood glucose temporarily. Because cats often show this stress response, vets may use repeat testing, fructosamine, urine testing and calm home readings alongside clinical signs rather than relying on one number.

Why the clinic can change the reading

Travel, handling, unfamiliar smells and restraint can all be stressful. The resulting rise can make diagnosis harder than it is in dogs.

How vets distinguish the possibilities

Your vet may combine repeat blood tests with fructosamine, urine testing and home monitoring. The aim is to understand the pattern and the wider clinical picture.

What this means for owners

If your vet says that retesting is needed, it does not mean your concerns are being dismissed. Keep notes on thirst, urination, appetite, weight and energy, and ask what to record at home.

When to contact your vet

Follow the testing plan your vet gives you. Urgent signs such as vomiting, food refusal, collapse or severe lethargy need prompt veterinary attention regardless of whether stress may be affecting glucose.

Read the cat diabetes symptoms guide, the fructosamine guide and the FAQ.

Sources

The pages below were each opened and checked before being listed here, and anything that could not be opened was left off rather than guessed at.

• How I Avoid Stress Hyperglycemia Confounding Glucose Measurement in Cats — WSAVA Congress Proceedings, Jacquie Rand and Mia Reeve-Johnson, 2017. The scale of the effect — struggling during handling can lift glucose by as much as 10 mmol/L — and the practical answer of retesting hours later with the cat quietly housed.
• 2025 iCatCare consensus guidelines on the diagnosis and management of diabetes mellitus in cats — Journal of Feline Medicine and Surgery 27:1–37, 2025. That stress hyperglycaemia can be of any magnitude, which is why confirmation uses home-collected samples taken at least two days after the stress.
• ISFM Consensus Guidelines on the Practical Management of Diabetes Mellitus in Cats — Journal of Feline Medicine and Surgery 17(3):235–250, 2015. That stress must be ruled out before treatment starts, and that fructosamine is less disturbed by it.
• Diabetes Mellitus in Dogs and Cats — MSD Veterinary Manual, reviewed May 2024, updated May 2026. That stress hyperglycaemia is common in cats, that several samples may be needed, and that fructosamine reads normal when stress was the cause.
• 2026 AAHA Diabetes Management Guidelines for Cats — American Animal Hospital Association, 2026. That the diagnosis should be documented in an unstressed or home environment, and that in-hospital curves are not recommended.