Why is my cat drinking and urinating so much all of a sudden?

Excessive thirst (polydipsia) and excessive urination (polyuria) happen in diabetic cats because glucose builds up in the bloodstream faster than the kidneys can reabsorb it. Once blood glucose climbs above roughly 200 to 280 mg/dL, the kidney's reabsorption threshold is exceeded and sugar spills into the urine, pulling water along with it osmotically and forcing the cat to urinate far larger volumes than normal (Cornell Feline Health Center, n.d.). The cat then drinks more to compensate for the fluid loss, which is why owners often describe refilling water bowls multiple times a day or noticing unusually heavy, saturated clumps in the litter box.

This mechanism is the same one that produces the classic sweet-smelling urine in unmanaged human diabetes, though most owners notice the volume long before any odor change. Veterinarians consider polyuria and polydipsia together one of the most consistent early indicators of diabetes in cats, alongside weight loss despite a normal or increased appetite, and they typically prompt same-week diagnostic testing rather than a wait-and-see approach (Merck Veterinary Manual, 2024).

What other early symptoms do cats with diabetes show besides drinking a lot?

Beyond thirst and urination, many diabetic cats lose muscle mass along the spine and hips even while maintaining or increasing their food intake, because their cells can't take up glucose for energy without adequate insulin and the body starts breaking down fat and muscle instead. Owners frequently describe a cat that "eats constantly but looks thinner," which is a red flag worth mentioning specifically to a veterinarian rather than attributing to old age (American Association of Feline Practitioners, 2022).

A subtler but important sign is a change in gait: some diabetic cats develop diabetic neuropathy, walking with their hocks touching the ground in a flat-footed, plantigrade stance rather than up on their toes. This occurs because sustained high blood sugar damages peripheral nerves over weeks to months, and it can be one of the first things a veterinarian notices on physical exam even before lab results come back (Cornell Feline Health Center, n.d.). Lethargy, unkempt-looking fur from reduced grooming, and increased hunger (polyphagia) round out the common early picture.

Which cats are most likely to develop diabetes?

Obesity is the single strongest modifiable risk factor identified in feline diabetes research; cats that are obese have been found to be roughly three to five times more likely to develop the disease than cats at a healthy weight, largely because excess fat tissue drives insulin resistance (AVMA, 2023). Middle-aged to senior cats, generally over 7 years old, and neutered male cats are also overrepresented in diagnosed cases, and Burmese cats have shown a notably higher predisposition in studies from Australia, New Zealand, and the UK.

Other contributing factors include physical inactivity, long-term corticosteroid use (such as prednisolone for allergies or asthma), and chronic pancreatitis, which can damage the insulin-producing beta cells in the pancreas over time. Unlike type 1 diabetes in humans, most diabetic cats have a disease pattern closer to human type 2 diabetes, where the body still produces some insulin but tissues respond to it poorly, which is part of why early weight management and diet change can sometimes reverse the condition (Cornell Feline Health Center, n.d.).

How do vets actually confirm a diagnosis of feline diabetes?

Diagnosis starts with a fasting blood glucose test, but a single elevated reading isn't enough on its own because cats are notorious for stress hyperglycemia — a temporary spike in blood sugar triggered simply by the anxiety of a vet visit or car ride. To rule that out, veterinarians rely heavily on a fructosamine blood test, which reflects average blood glucose over the prior 1 to 3 weeks and isn't affected by short-term stress (Cornell Feline Health Center, n.d.).

A urinalysis checking for glucosuria (glucose in the urine) and ketones is run alongside bloodwork, since persistent glucose in urine combined with elevated fasting glucose and fructosamine confirms the diagnosis. Vets typically also order a complete blood count and chemistry panel to screen for concurrent conditions like pancreatitis, hyperthyroidism, or kidney disease that commonly coexist with diabetes in older cats and can complicate treatment planning (Merck Veterinary Manual, 2024).

What does treating a diabetic cat actually involve day to day?

Most diabetic cats are managed with twice-daily insulin injections given roughly 12 hours apart, typically starting with a long-acting insulin such as glargine (brand name Lantus or its veterinary equivalent) or PZI insulin, dosed by the veterinarian based on body weight and blood glucose curves (AAHA, 2023). Injections are given subcutaneously with a very fine needle, and most owners report that cats tolerate them far better than expected once a routine is established, usually right around a meal.

Diet plays an outsized role in feline diabetes management compared to some other chronic diseases: switching to a low-carbohydrate, high-protein canned diet has been shown in multiple studies to improve glycemic control and increase the odds of diabetic remission, particularly when started soon after diagnosis (WSAVA, 2021). Consistent meal timing matched to insulin dosing, avoiding free-feeding of dry food, and maintaining a stable weight are all part of the daily routine a vet will build with the owner.

Can a diabetic cat go into remission and stop needing insulin?

Diabetic remission — where a cat maintains normal blood glucose without ongoing insulin — happens in an estimated 20 to 65% of newly diagnosed cats, with the wide range reflecting differences in how early treatment starts and how tightly glucose is controlled (Cornell Feline Health Center, n.d.). Remission is most likely when insulin therapy and dietary change begin within the first few months of diagnosis, before prolonged high glucose permanently damages the pancreas's remaining beta cells, a phenomenon researchers call glucose toxicity.

Even cats that achieve remission need lifelong monitoring, because relapse is common, especially if weight is regained or a new illness triggers insulin resistance. Home blood glucose monitoring using a glucometer or a continuous glucose monitor patch designed for veterinary use has become increasingly common and lets owners catch early swings before a full relapse develops (AAHA, 2023).

How do I check my cat's blood sugar and avoid a dangerous insulin overdose at home?

Many veterinarians now teach owners to perform at-home glucose curves using a handheld glucometer and a lancet on the ear pinna or paw pad, checking glucose every 2 to 4 hours around insulin doses to help fine-tune dosing without repeated stressful vet visits. Some clinics instead prescribe a flash glucose monitoring sensor that sticks to the skin and logs readings continuously for up to 14 days, giving a fuller picture than single spot checks (AVMA, 2023).

The biggest home-care risk is hypoglycemia from an insulin overdose or a missed meal after dosing, which can cause weakness, wobbliness, or seizures within hours. Owners are generally advised to keep a source of fast-acting sugar, such as corn syrup, on hand to rub on the gums in a suspected low-glucose emergency, then get to a veterinarian immediately, and to never adjust insulin doses without veterinary guidance based on a real glucose curve (Merck Veterinary Manual, 2024).