The number of cats with diabetes has more than doubled in the last year.
Vets blame indulgent owners who over-feed their pets.
The disease that is most commonly caused by obesity and advancing age.
Cases of feline diabetes has increased by over 130%, according to data from Argos Pet Insurance.
Fatty felines' diabetes are costing their overindulgent owners an average of £1,880 in vet bills
And 78% UK vets report seeing a steady rise in pet obesity in the last two years.
Diabetes is now costing cat owners an average of £1,880 each in vet bills, more than triple the cost from a year ago.
Maia Boylla of Argos Pet Insurance, said: 'The fact that the number of cats being treated for diabetes has more than doubled over the last year is a worrying indicator of increased pet obesity in the UK.
'This is a big eye opener for cat owners, as many probably don't realise just how much damage can be done from a few too many treats.'
78% of British vets report seeing a rise in pet obesity in the last two years
Other factors that can contribute to the development of diabetes in cats include old age, neutering and a generally inactive lifestyle.
Resident veterinary consultant for Argos Pet Insurance, Andrew Moore, said: 'Diabetes is more common in middle-aged and older cats. Overweight and neutered cats are also at greater risk of the disease, which is commonly linked to obesity and an inactive lifestyle.
'Symptoms of diabetes include increased urination, increased thirst, increased appetite and unexplained weight loss.
Vets and researchers blame overly indulgent owners giving their pets too much food
'It can be treated with medication or injections, but to minimise the risk of the disease, owners should take steps to keep their cats fit and healthy.'
Maia said: 'Even if your cat appears fit and healthy at the moment, it's worth making sure they're protected with pet insurance from the outset, to help you avoid large unexpected vet fees if your cat develops health complications in later life.'