Feline Acromegaly and Diabetes: Why Some Cats Need Very High Insulin Doses

Feline acromegaly and diabetes

Quick answer

Acromegaly is a growth hormone disorder, usually caused by a small pituitary tumour, that makes diabetes very difficult to control. Research has found signs of it in around a quarter of cats whose diabetes has proven hard to manage. It's identified with a blood test and, in cats where it's confirmed, there are treatment options — so it's worth raising with your vet if your cat needs unusually high insulin doses despite everything else being consistent.

Species: Cats

Key takeaways

• Acromegaly is one possible explanation for genuinely difficult-to-stabilise diabetes, not a diagnosis you can make from signs alone.
• Excess growth hormone can block insulin from working properly.
• An IGF-1 blood test is commonly used to investigate it, sometimes followed by imaging.
• Most diabetic cats do not have acromegaly.
• Treatment options exist, but decisions belong with your vet and, where needed, a specialist.

What growth hormone does

Growth hormone helps regulate growth and how the body uses energy. In acromegaly, the body produces too much growth hormone, usually because of a small tumour in the pituitary gland. Excess growth hormone can make the body's tissues less responsive to insulin, which is why diabetes may become difficult to control.

This explanation is educational only. If you are worried about your cat's response to treatment, raise the pattern with your vet rather than changing insulin or any other treatment yourself.

The pattern an owner might notice

A cat with acromegaly may need unusually high insulin doses despite consistent feeding, insulin handling and monitoring. Some owners notice a broadening face or larger-looking head, louder breathing or snoring, or weight gain later in the disease course rather than the weight loss often associated with uncontrolled diabetes.

These changes can have many explanations and are not diagnostic. A cat does not need to show all of them, and a cat with one of them does not necessarily have acromegaly. They are simply details to mention to your vet.

Why it is more common in cats than dogs

Feline acromegaly has been recognised as an important differential diagnosis in difficult diabetic cats. It is less commonly discussed in dogs, and the evidence and clinical approach differ between species. Your vet will interpret the species, history, examination and test results together.

How it is diagnosed

A vet may investigate acromegaly with an IGF-1 blood test. Depending on the result, clinical pattern and local expertise, further assessment or imaging may be discussed. A test result is not something to interpret in isolation, and your vet will explain what it means for your cat.

If diabetes is proving difficult to stabilise, bring your Mello record of doses, readings, appetite, weight and energy to the appointment. Home glucose monitoring can help you keep information together when your vet has asked you to monitor at home.

Treatment options

Where acromegaly is confirmed, treatment options may include radiotherapy and, more recently, medical management. The right approach depends on the individual cat, available expertise, test results, overall health and your veterinary team's advice. Never change insulin or add, stop or adjust medicine based on this guide.

What to ask your vet

You could ask:

• Could my cat's pattern be worth investigating for acromegaly or another cause of insulin resistance?
• Would an IGF-1 blood test be appropriate?
• What other causes should we check first?
• Would a referral to a veterinary specialist help?
• What information should I record before the next review?
• Which changes mean I should contact you sooner?

This is uncommon, but worth knowing about

This is not a common condition, and most diabetic cats do not have it. It's simply one of the explanations vets consider when a cat's diabetes proves genuinely difficult to stabilise despite a consistent routine.

Frequently asked questions

What is acromegaly in cats?

It is a growth hormone disorder, usually caused by a small pituitary tumour, that can make diabetes difficult to control.

How common is acromegaly in diabetic cats?

Research has found signs suggestive of it in around a quarter of some cohorts of diabetic cats with difficult-to-manage diabetes. Most diabetic cats do not have it.

What are the signs of acromegaly?

The pattern can include unusually high insulin requirements despite consistency, a broadening face, a larger-looking head, louder breathing or snoring, and later weight gain. These signs are not diagnostic.

How is acromegaly diagnosed?

A vet may use an IGF-1 blood test and sometimes imaging or specialist assessment. Your vet should interpret the result in context.

Can acromegaly in cats be treated?

There may be options including radiotherapy and medical management. A veterinary specialist should guide treatment decisions.

Sources and further reading

• Niessen SJM et al. “Feline acromegaly: an essential differential diagnosis for the difficult diabetic.” Journal of Feline Medicine and Surgery.
• Why won't my pet's diabetes stabilise?
• Diabetic pet life expectancy
• Home glucose monitoring
• Mello FAQ

This guide is for general education, not diagnosis or treatment. Always follow your own vet's instructions and never change insulin without veterinary direction.

Use Mello to keep a clear record for your veterinary team.

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Last updated: 9 August 2026
Reviewed by: Mello Editorial Team

Mello helps diabetic pet owners track routines, spot patterns and share clearer updates with their veterinary team.