Diabetes mellitus in dogs

Author: Caroline Burke BSc, NCert(SAN) RVN, Royal Canin Health Affairs Manager (UK&I) 

Diabetes mellitus is a relatively common condition in dogs; in fact, it has an estimated prevalence rate of 0.26–1.33%.¹ So, if your dog has recently been diagnosed with this chronic, lifelong condition, you are not alone. And whilst their new diagnosis might mean you have to make changes to yours and your pet’s daily routine, with the right management plan, there is no reason why your diabetic dog can’t live a healthy and happy life.²

Like humans, dogs rely on insulin from the pancreas to control their blood glucose (blood sugar) levels. In healthy dogs, blood glucose levels increase after a meal and the pancreas releases insulin in response. Insulin acts as a “key”, unlocking the cell receptors and allowing the cells in the muscles, liver and other tissues to absorb and use glucose from the blood.

In dogs with diabetes, the pancreas fails to produce enough insulin, which means that there aren’t enough “keys” to unlock the cell receptors, meaning the tissues cannot absorb and use glucose, leading to persistently high blood sugar levels and the clinical signs you may see. ³ This type of diabetes is like type-1 diabetes in humans.³

The signs you might see can be quite subtle, at least initially, but left untreated they will progress to becoming more obvious and more serious. 

One of the most common signs you might spot is your dog losing weight, despite them eating as much, if not more, food than they normally would. This is because even though they are eating well, their body cannot access the energy from their food, and as a result they start to lose weight and may also become lethargic. 

At the same time, the blood sugar levels in your dog’s bloodstream start to increase, as the cells in the body can’t utilise glucose. Once blood sugar levels reach a high enough level, glucose starts to spill out into your dog’s urine, pulling water along with it. This means that diabetic dogs may pass larger volumes of urine and urinate more frequently. You may also notice that your dog is drinking more; this is because they are trying to replace the water they are losing in their urine. 

Without an effective management plan in place, the signs of diabetes are likely to worsen, and dogs can experience complications such as infections, cataracts and diabetic ketoacidosis (DKA) (a life-threatening condition caused by uncontrolled diabetes – veterinary treatment should be sought immediately if your dog is affected by DKA).³ 

There are several factors that may put your dog at an increased risk of developing diabetes mellitus, including:   

• Age: Diabetes mellitus typically develops between 5 to 12 years of age¹, but middle-aged dogs (over 8 years of age) are at higher risk.⁴
• Size: Dogs with an ideal bodyweight <22kg have a significantly greater risk of developing diabetes mellitus.⁷ In fact small breed dogs represent up to 60% of cases.^1,6
• Breed: Some breeds, including Tibetan Terriers, Miniature Schnauzers, Cairn Terriers, Samoyeds and Border Terriers have been reported as being higher risk.^1,4,6
• Sex: Neutered male and intact female dogs are at increased risk⁴
• Obesity: Dogs with overweight or obesity are 3.5 times more likely to develop diabetes mellitus than dogs of an ideal weight.⁵ 

It’s important to remember that even if you dog falls into one or more of these categories it doesn’t mean that they will develop diabetes mellitus. If you are concerned about your dog’s risk of developing diabetes mellitus then it’s best to speak to your veterinary team who can assess your dog’s health and provide advice on how to manage, or possibly even reduce, the risk; for instance, developing a weight loss programme if your dog has overweight or obesity.  

If you are concerned that your dog is showing signs of diabetes mellitus, then you need to speak to your veterinary team. 

The main goal of management plans for dogs with diabetes mellitus is to control blood sugar levels and limit the occurrence of signs like excessive thirst and urination. As a general guide, management plans for dogs with diabetes will centre around 3 key areas:^3,4 

1. Medication: Since dogs with diabetes are unable to make their own insulin, treatment requires insulin injections; either once or twice daily, depending on the insulin used.
2. Nutrition: Alongside medication, a diet specially formulated for dogs with diabetes can help in the management of blood sugar levels after meals.
3. Weight management: Your veterinary team may also look at supporting your dog’s weight, as dogs with diabetes mellitus may be underweight or overweight.

As each dog is an individual, your veterinary team will work with you to develop a management plan that is tailored to your dog’s individual needs. 

Diets that have been specifically formulated for diabetic dogs have several nutritional adaptations including: 

• Reduced digestible carbohydrate (starch) content: Simple carbohydrates (such as starch) are digested quickly and therefore cause rapid spikes in blood glucose levels after meals. Whereas complex carbohydrates are digested slowly and therefore provide a more steady and sustained release of glucose, which helps to limit spikes in blood sugar levels after eating. Therefore, diets for diabetic dogs are formulated with a low starch content and an increased content of complex carbohydrates, both of which help in the management of blood glucose levels after meals.
• A blend of fibres: Fibres can help to slow down digestion and absorption of glucose, which helps to support blood glucose levels.
• High protein content: Protein is one of the main building blocks of muscle, so feeding a diet with a high protein content helps to maintain lean muscle mass.
• Moderate energy content: Due to the link between obesity and diabetes mellitus, it stands to reason that a diet for a diabetic dog would have a calorie content adapted to help maintain an ideal weight and shape. 

Royal Canin® Glycobalance is a range of diets that have been specifically formulated to help in the management of blood glucose levels after meals in diabetic dogs and support a healthy weight in diabetic dogs. The diets in this range are complete and balanced and follow the nutritional principles detailed above. Royal Canin® Glycobalance is available in 3 formats:  

• Royal Canin® Glycobalance small dogs dry is formulated for diabetic small dogs (<10 kg) and helps support the specific digestive, dental and urinary sensitivities of small dogs with adapted kibble for small jaws.
• Royal Canin® Glycobalance dry is formulated for diabetic dogs with an adult body weight >10 kg.
• Royal Canin® Glycobalance wet can be fed on its own or in combination with either Royal Canin® Glycobalance small dogs dry or Royal Canin® Glycobalance dry.

Your vet may recommend feeding Royal Canin® Glycobalance during stabilisation (which may take 4-12 weeks) and once fair to good glycaemic control has been achieved, the nutritional recommendation may vary according to body condition score (BCS): 

• If your dog has a BCS ≤ 6/9 your veterinary team may recommend continuing to feed a diet(s) from within the Royal Canin® Glycobalance range.
• If your dog has a BCS ≥ 7/9 your veterinary team may recommend transitioning to a diet that can help to support weight reduction, for instance a diet from within the Royal Canin® Satiety Weight Management range.

Your veterinary team are best placed to be able to guide you as to which diet to feed and if/when to change diets, as well as what monitoring needs to be put in place before changing diets. It is therefore critical that you speak to them before changing your dog’s diet or feeding volume. 

To learn how to assess your pet's body shape using the Body Condition Score (BCS), read our article on Managing your pet’s weight.

As well as recommending feeding a diabetic diet, your veterinary team will likely discuss the importance of sticking to the same routine with your dog; but what does this actually mean?   

• Meals: Feed the same amount, of the same diet, at the same time, every day. Dogs will generally need to be fed twice a day (meals will be roughly 12 hours apart), but you will need to discuss this with your veterinary team and follow their specific recommendations for your dog. Weighing out the daily food portion using digital scales is recommended to ensure an accurate food portion.
• Medication: Give your dog the veterinary advised amount of insulin shortly after they have eaten, at approximately the same time(s) of the day (insulin may be given once or twice a day). Again, your veterinary team will advise how much and how often to give your dog their medication.
• Exercise: You will need to maintain a consistent exercise routine with your dog, rather than lots of sporadic, high energy exercise sessions. 

Managing a diabetic dog can feel overwhelming at first, and it may take time to find the right dose of medication and management plan for your dog, but you will be surprised at how quickly both you and your dog adapt to the new routine. Your veterinary team are best placed to be able to help support and advise you and alongside medication, they may recommend feeding a diet that is tailored to meet the specific needs of diabetic dogs. Diets within the Royal Canin® Glycobalance range have been specifically formulated to help in the management of blood glucose levels after meals in diabetic dogs and support a healthy weight in diabetic dogs. 

Article sponsored by ROYAL CANIN© 

1. Denyer AL, O’Neill DG, Brodbelt DC, Holder A, Catchpole B, Davison LJ. Epidemiology and clinical management of 1072 dogs with diabetes mellitus in a UK diabetes register. Companion Anim Health Genet. 2025 Oct 10;12:7.
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