Diabetes in Dogs: The Other Health Problems to Watch For

Katherine Allen

If your dog has diabetes, you're already managing insulin shots and keeping an eye on glucose numbers. What doesn't always come up at the first vet visit is that diabetes can lead to other health problems. Some show up slowly over months. A couple of them are emergencies.

I'm not a vet. This post pulls together what veterinary research and vet schools say about these conditions, with links so you can read the sources yourself. Your vet knows your dog, so take questions about your dog to them.

Slow Problems and Emergencies

Cataracts and urinary tract infections tend to build over weeks or months. You catch them with regular vet checks and by paying attention at home. Diabetic ketoacidosis (DKA) and low blood sugar are different. If you see signs of either one, call your vet right away.

Not everything on this list is caused by diabetes. Pancreatitis can lead to diabetes, diabetes can raise the risk of pancreatitis, and researchers still don't know which one usually comes first (Davison, 2015). I'll point it out where the evidence isn't settled.

Cataracts

Cataracts are the most common complication. In a study of 200 diabetic dogs, half had cataracts about six months after diagnosis, 75% had them within a year, and 80% had them by about 16 months (Beam et al., 1999). Good blood sugar control doesn't prevent them in dogs the way it helps in people. When there's extra glucose in the lens, a dog's body turns it into sorbitol. Sorbitol pulls water into the lens, and the lens clouds over. Most diabetic dogs end up with cataracts no matter how well their diabetes is managed (Merck Veterinary Manual; Cornell Riney Canine Health Center).

What to watch for:

Bluish-white or gray cloudiness in one or both eyes
Bumping into furniture or hesitating at stairs
Getting startled more easily than usual
Losing vision fast. Diabetic cataracts can develop over a few days, and some dogs can see one day and can't the next (Cornell).

Don't put this one off. Diabetic cataracts often cause inflammation inside the eye (uveitis), which can lead to glaucoma, and glaucoma is hard to treat in these dogs (Cornell). Cataract surgery can restore vision in a lot of dogs, so ask your vet early about a referral to a veterinary ophthalmologist.

Diabetic Ketoacidosis (DKA)

When a dog's cells can't get glucose, the body starts burning fat for fuel. If that goes too far, ketones build up and the blood becomes acidic. That's DKA. It's life-threatening and one of the leading causes of death in diabetic dogs that aren't being treated (Cornell). DKA is often set off by another illness, like a UTI or pancreatitis, so vets check for those when a dog comes in with DKA (Merck Veterinary Manual).

Signs of DKA:

Vomiting, diarrhea, or not eating
Severe weakness and lethargy, well past normal tiredness
Dehydration: dry, sticky gums or sunken eyes
Fast or labored breathing
Breath that smells sweet or like nail polish remover (not every dog with DKA has this)
Wobbliness, collapse, or seizures in advanced cases (VCA; PDSA)

If your diabetic dog stops eating or starts vomiting, call your vet. Don't wait until morning to see if it passes (PDSA).

Low Blood Sugar (Hypoglycemia)

Low blood sugar comes from insulin treatment, not from diabetes itself. It happens when a dog has more insulin than the food in its system can cover. Common causes are a skipped or vomited meal, an accidental double dose, more exercise than usual, or the dog needing less insulin than before (Merck Animal Health). It can turn fatal quickly.

Signs of low blood sugar:

Weakness, stumbling, or walking like they're drunk
Trembling or muscle twitching
Restlessness, anxiety, or whining
Confusion or a glassy-eyed stare
Seizures, collapse, or unconsciousness (Merck Animal Health; AVMA)

If your dog is conscious, rub a little corn syrup or honey on the gums. Don't pour it into the mouth, because your dog could inhale it. Offer food once your dog can swallow, and call your vet (Merck Animal Health). If your dog is having a seizure or won't respond, go to the emergency vet and bring the insulin and syringes with you (American Red Cross).

Urinary Tract Infections (UTIs)

Sugar in the urine feeds bacteria, so diabetic dogs get UTIs more often, and the infections can keep coming back (Merck Veterinary Manual). One study found bacteria in the urine of about 21% of diabetic dogs (dvm360). About half of dogs with a UTI don't show any urinary signs (dvm360). That's why the AAHA diabetes guidelines recommend a urine culture at diagnosis and again periodically. A urine sample that looks normal under the microscope doesn't rule out an infection (AAHA). An untreated UTI can make diabetes harder to control, and it can be what pushes a dog into DKA (Merck Veterinary Manual).

Signs of a UTI:

Straining to pee, peeing small amounts often, or accidents in the house
Cloudy or bloody urine, or a strong smell
Licking the genital area a lot
No signs at all, which is why regular urine checks matter (VCA)

Pancreatitis

The pancreas makes digestive enzymes and it makes insulin, so it makes sense that pancreatitis and diabetes overlap. Studies have found signs of pancreatitis in about 28 to 40% of diabetic dogs. Many vets think pancreatitis leads to diabetes more often than the other way around, but there's evidence for both (Catchpole et al., 2005; Davison, 2015; 2022 review).

A newer analysis found diabetic dogs were more than 12 times as likely to develop acute pancreatitis, and high blood triglycerides seem to be part of the reason (Veterinary Times). When a dog has both, blood sugar is often harder to keep steady. If your dog's diabetes suddenly gets harder to control, ask your vet about checking for pancreatitis (Davison, 2015).

Signs of pancreatitis:

Vomiting and not eating
Lethargy
Belly pain: a hunched back, the "prayer position" stretch, or flinching when you touch the belly (Merck Veterinary Manual)

I wrote about what I wish someone had explained to me about pancreatitis when my own dog went through it. If you want the deeper guide, there's The Dog Parent's Survival Guide: Pancreatitis.

Less Common Complications

These don't happen often in dogs, but you should know they exist.

Diabetic neuropathy. Nerve damage from diabetes is mostly a cat problem and is rare in dogs. When dogs do get it, it shows up as weak back legs and muscle loss (Merck Veterinary Manual).

Hyperosmolar hyperglycemic state (HHS). Blood sugar gets extremely high and the dog becomes severely dehydrated, but without ketones. These dogs are usually very lethargic or unconscious. It's an emergency (Merck Veterinary Manual).

Kidney and blood vessel damage. In people, diabetes often leads to kidney failure, damaged blood vessels in the eyes, strokes, and heart attacks. These are rare in dogs (Merck Veterinary Manual). Some diabetic dogs get minor changes in the retina (about 13% of diabetic dogs with eye symptoms in one study), but those rarely affect vision the way cataracts do (Salgado et al., 2023).

Skin and other infections. High blood sugar weakens the immune system, so keep an eye out for skin infections and UTIs that keep coming back (AVMA; Cornell).

Quick Reference

What you see	Possible cause	What to do
Cloudy eyes, bumping into things	Cataracts	Vet visit within a few days for an eye exam
Vomiting, not eating, sweet breath, fast breathing	DKA	Call your vet now; emergency clinic after hours
Wobbly, trembling, glassy stare	Low blood sugar	Corn syrup on the gums, then call your vet
Straining to pee, accidents, cloudy urine	UTI	Vet visit within a few days
Vomiting, hunched back, belly pain	Pancreatitis	Same-day vet visit
Weak back legs, muscle loss	Neuropathy (rare)	Vet visit

The Bottom Line

Plenty of diabetic dogs live for years after diagnosis. Learn the signs of DKA and low blood sugar now, before you need them. Keep up with vet visits and urine checks, because that's how the slower problems get caught early. If your dog's diabetes suddenly gets harder to control, ask your vet about infection and pancreatitis by name.

Want the Full Guide?

If your dog was just diagnosed, The Dog Parent's Survival Guide: Diabetes walks through all of this in one place, the day-to-day management plus what to watch for and when to call the vet.

For appointments, the Diabetes Care Planner & Vet Question Workbook puts the daily logs and vet questions in one printable you can take with you.

Educational use only. This post is not a substitute for professional veterinary advice, diagnosis, or treatment.

Sources

Beam, A., Correa, M., & Davidson, M. (1999). A retrospective-cohort study on the development of cataracts in dogs with diabetes mellitus: 200 cases. Veterinary Ophthalmology.
Catchpole, B., et al. (2005). Canine diabetes mellitus: can old dogs teach us new tricks? Diabetologia.
Cornell University Riney Canine Health Center: Canine cataracts
Cornell University Riney Canine Health Center: Diabetes in dogs
Cornell University Riney Canine Health Center: Managing canine diabetes
New insights into the etiology, risk factors, and pathogenesis of pancreatitis in dogs (2022). Veterinary Sciences.
Davison, L. (2015). Diabetes mellitus and pancreatitis: cause or effect? Journal of Small Animal Practice.
dvm360: Top ten questions about UTIs
dvm360: Managing difficult urinary tract infections
2018 AAHA Diabetes Management Guidelines for Dogs and Cats (2022 update)
American Red Cross: Hypoglycemia in dogs
AVMA: Diabetes in pets
Merck Veterinary Manual: Diabetes mellitus in dogs and cats
Merck Veterinary Manual: The lens in animals
Merck Veterinary Manual: Infectious diseases of the urinary system in dogs
Merck Veterinary Manual: Pancreatitis in dogs
Merck Veterinary Manual: Metabolic disorders of the peripheral nerves
Merck Animal Health: Handling a diabetes emergency
PDSA: Diabetes in dogs
Salgado, D., et al. (2023). Prevalence of ocular findings and their association with glycemia in diabetic dogs.
VCA Animal Hospitals: Diabetic ketoacidosis in dogs
VCA Animal Hospitals: Urinary tract infections in dogs
Veterinary Times: Acute pancreatitis problems in dogs, what's new? Part one

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