Diabetes in Dogs: Signs, Diagnosis and Daily Care

At a glance

What it is	A long-term condition where the body cannot produce enough insulin to control the level of sugar in the blood
Who's at risk	Mostly middle-aged and older dogs; unneutered females, overweight dogs and some breeds may be more likely to develop it
Main signs	Drinking more, peeing more, increased appetite, weight loss and, later, cloudy eyes
Contagious?	No
Can it be prevented?	Not always, but keeping your dog a healthy weight and seeing your vet early about changes helps

What it is

When your dog eats, food is broken down into sugar, mainly a type called glucose, which travels in the blood to give the body energy. For that sugar to move from the blood into the cells that need it, the body uses a hormone called insulin.

Insulin is made by the pancreas, a small organ near the stomach. You can think of insulin as a key that unlocks the body's cells so they can take in sugar. In most diabetic dogs, the cells in the pancreas that make insulin have been damaged or lost, so there are not enough keys. This is similar to type 1 diabetes in people, and it means most diabetic dogs need insulin for the rest of their lives.

Without enough insulin, sugar builds up in the blood while the body's cells are effectively starving. The body starts breaking down fat and muscle for energy, which is why dogs lose weight even when they are eating well. The kidneys try to get rid of the extra sugar through urine, and that sugar draws water with it, which leads to more peeing and, in turn, more drinking.

The exact reason a dog's pancreas stops making insulin is not always clear. Genetics, previous inflammation of the pancreas, certain hormonal conditions and some medicines can all play a part. In unneutered female dogs, hormones linked to the heat cycle can make diabetes more likely or harder to control.

Signs to watch for

The classic early signs of diabetes in dogs are:

• Drinking more. You may find yourself refilling the water bowl more often, or see your dog drinking from puddles, the toilet or the garden.
• Peeing more. Larger amounts, more frequent trips outside, needing to go in the night, or accidents indoors from a dog who is normally clean.
• Increased appetite. Your dog may seem hungry all the time or start scavenging.
• Weight loss. Despite eating well or more than usual, your dog may lose weight and muscle, particularly along the back and back legs.

Other signs can include:

• Tiredness or less interest in walks
• A dull or thin coat
• Repeated urinary infections
• Cloudy eyes. Diabetes commonly leads to cataracts in dogs, which make the lens of the eye look cloudy or milky blue-white. These can develop quite quickly and may affect your dog's sight.

These signs can creep up slowly, so they are easy to put down to age or the weather. Increased thirst in particular can be caused by many different conditions, so it is always worth having it checked. Our guide on why your dog might be drinking more water explains some of the possibilities, and our symptom checker can help you decide how soon to seek help.

• 💧

  Drinking more

  Emptying the water bowl faster than usual.

• 🚽

  Peeing more

  More or bigger wees, accidents, heavier litter clumps.

• 🍽️

  Eating more

  Hungrier than usual — sometimes ravenous.

• ⚖️

  Losing weight

  Despite eating well, often the most surprising sign.

When to see a vet

Book an appointment with your vet if you notice your dog drinking or peeing more than usual, losing weight without trying, or developing cloudy eyes. It helps to bring a note of how much your dog is drinking over a day or two if you can measure it.

Contact your vet urgently if your dog has signs of diabetes along with any of the following:

• Vomiting or diarrhoea
• Not eating
• Marked tiredness, weakness or seeming very unwell
• A sweet or unusual smell on the breath
• Fast or heavy breathing

These can be signs of a serious complication called diabetic ketoacidosis, which happens when the body breaks down fat too quickly and harmful substances build up in the blood. It needs emergency treatment.

How vets diagnose it

Your vet will examine your dog and ask about their thirst, appetite, weight and toilet habits. To diagnose diabetes, they will usually carry out:

• Blood tests to measure the level of sugar in the blood. They may also run a test that reflects average blood sugar over the previous couple of weeks, which helps distinguish true diabetes from a short-term rise caused by stress.
• Urine tests to look for sugar and ketones in the urine, and to check for a urinary infection, which is common in diabetic dogs.

Your vet will often run a wider blood panel too. This checks other organs and looks for conditions that can occur alongside diabetes or make it harder to control, such as pancreatitis or hormonal disorders. You can read more in our article on pancreatitis in dogs.

Treatment and management

Most diabetic dogs are managed with insulin injections given under the skin, usually around mealtimes. The thought of injecting your dog can feel daunting, but the needles are very fine, and most owners and dogs get used to the routine quickly. Your vet or veterinary nurse will show you how to store the insulin, prepare the injection and give it calmly.

Your vet will choose the right type of insulin and decide on the amount. Never change the amount or timing yourself. Getting the dose right often takes a few weeks of adjustments, so expect several follow-up visits at the start.

Consistency is key

Diabetes is easiest to manage when each day looks much the same. Your vet will usually recommend:

• Consistent meals. The same food, in the same amount, at the same times each day. Your vet may suggest a particular diet. Measuring food carefully, rather than guessing, makes a real difference.
• Consistent exercise. Similar amounts of activity each day. A sudden long run or a very active day uses up more sugar and can lower blood sugar more than expected.
• Minimal extras. Treats and titbits can upset the balance, so talk to your vet about what is suitable.

If your dog is an unneutered female, your vet may recommend neutering, as hormones from the heat cycle can make diabetes much harder to control. If your dog is overweight, gradual, vet-guided weight loss can also help.

Monitoring at home

Your vet will explain how to keep an eye on your dog's diabetes at home. This may include:

• Keeping a daily diary of meals, insulin given, water intake, energy levels and any unusual signs
• Checking urine for sugar or ketones with test strips
• Measuring blood sugar at home with a handheld meter or a sensor, if your vet thinks this is suitable for you and your dog
• Regular blood sugar checks at the clinic, sometimes measured over a whole day to see how levels change between injections

Tracking water intake and weight is one of the simplest and most useful things you can do. A dog whose diabetes is well controlled typically drinks less, keeps a steady weight and has good energy. Many owners use a notebook, a spreadsheet or a tool like Petopedia's pet calculators to keep an eye on weight and feeding. Bring your notes to every check-up.

Low blood sugar is an emergency

The most important risk to understand is low blood sugar, called hypoglycaemia. It can happen if a dog gets too much insulin, misses a meal, vomits after eating or has much more exercise than usual. Signs include:

• Weakness, tiredness or seeming dull
• Wobbliness, trembling or stumbling
• Confusion or unusual behaviour
• Collapse or seizures

If you see any of these signs, treat it as an emergency and contact your vet immediately. Your vet will explain in advance what first aid you can give at home while you get help, so ask about this at your first visit and keep the instructions somewhere easy to find.

Also contact your vet if your dog will not eat or vomits after a meal, so they can advise you on what to do about the next insulin injection rather than guessing.

Prevention

Not all cases of diabetes in dogs can be prevented, as genetics play a part. However, you can reduce some risks:

• Keep your dog at a healthy weight. Being overweight affects how well the body responds to insulin. Our obesity in pets article explains how to tell if your dog is carrying extra weight.
• Talk to your vet about neutering if you have an unneutered female, as this can reduce one hormonal risk factor.
• Avoid fatty food scraps. These can trigger pancreatitis, which may damage the pancreas over time.
• Notice changes early. Keeping an eye on thirst, appetite and weight means diabetes and other conditions can be picked up sooner, before complications develop.

Living with it

A diagnosis of diabetes can feel overwhelming at first, but most owners find that it becomes a manageable part of daily life within a few weeks. The routine of measured meals, injections and steady exercise soon becomes second nature.

Cataracts are common in diabetic dogs, even when the diabetes is well managed. Many dogs adapt well to reduced sight, especially in a familiar home where furniture stays in the same place. Your vet can talk to you about eye care and whether referral to an eye specialist might be an option.

It helps to plan ahead for holidays, kennels and busy days, since your dog will need their meals and injections on time. Make sure anyone looking after your dog knows the routine and the signs of low blood sugar. With good care and regular vet checks, many diabetic dogs go on to enjoy a good quality of life for years.