In general terms, diabetes in a cat develops when the body cannot use blood sugar properly, and the signs that follow are mostly about water, weight and energy. They tend to creep in over weeks, so owners often adjust without realising: refilling the bowl more often, buying litter sooner, assuming an older cat is simply slimming down. Putting those small changes side by side is what turns them into a pattern worth discussing with a vet.
Thirst and urine are usually the first flags
The earliest and most consistent signs involve water. A cat may drink from the bowl more often, linger longer over it, or start seeking water from taps, glasses or plant saucers. Because more water goes in, more urine comes out: litter clumps become larger and more numerous, a tray fills faster than it used to, and some cats begin urinating outside the tray simply because it is wet sooner than expected. Measuring is better than guessing here. Note how often you refill a marked water bowl each day and roughly how many large clumps you scoop, for a week or two, and you will have numbers a vet can use. A sudden single thirsty day after salty treats or hot weather is different from a steady climb that persists.
Weight, appetite and energy changes
Alongside the thirst, many cats lose weight gradually even though they eat as much as ever, and some become noticeably hungrier, finishing meals fast and asking for more. Energy often dips: longer naps, less interest in play, and less jumping or exploring than before. Grooming can slip, leaving the coat dull or slightly scurfy, particularly along the back where a heavier cat struggles to reach. In some cats, weakness in the hind legs develops over time, seen as walking lower on the back feet with the hocks dropping toward the floor instead of up on the toes. None of these signs alone proves anything, since thyroid and kidney conditions can look similar, but weight loss combined with rising thirst and urine output is a combination vets take seriously.
What happens at the veterinary visit
A vet exploring this pattern will weigh the cat, review your water and litter notes, and typically check blood and urine to see how sugar levels are behaving and to rule out look-alike conditions. That is also why home records matter: a single stressful clinic visit can nudge blood sugar readings in cats, so evidence of a persistent home pattern helps the vet interpret results sensibly. Bring details of current food, feeding amounts and any recent weight change, plus a note of other signs such as vomiting, appetite swings or infections that keep returning. If diabetes is confirmed, the vet will explain a management plan built for that individual cat, and monitoring at home becomes part of daily life rather than a one-off test.
When these signs should not wait
Book an appointment promptly if thirst and urination have clearly increased for more than a few days, especially with weight loss alongside. Seek a vet the same day if a cat with these signs stops eating, vomits, becomes very lethargic or breathes oddly, because a cat who feels unwell on top of this pattern can deteriorate quickly. Acting on the trend early gives the best chance of a straightforward plan. Keeping your refill counts, litter notes and weight entries together in your KinsLe Pet Passport, a pet's records in one portable packet ready for vet visits, ensures that pattern is documented rather than reconstructed from memory.