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Diabetes Mellitus in Dogs - Symptoms and Treatment

Josie F. Turner
By Josie F. Turner, Journalist specialized in Animal Welfare. Updated: February 28, 2024
Diabetes Mellitus in Dogs - Symptoms and Treatment

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Diabetes mellitus is one of the most frequent chronic diseases diagnosed in small animal veterinary clinics. For some dog guardians, it is surprising since dogs do not generally eat a lot of sugar in their diet, but this is due to a mischaracterization of the disease. Despite such prevalence, especially in older female dogs, greater awareness is required to both observe for signs of the disease and prevent its development. The first factor we should be aware of is that a dog with diabetes mellitus can enjoy a good quality of life with proper treatment management.

At AnimalWised we explain more about the causes, symptoms and treatment of diabetes mellitus in dogs. We also provide information on how it may be diagnosed and what we can do to prevent it in our dog.

You may also be interested in: Diabetes in Dogs
  1. What is diabetes mellitus in dogs?
  2. Causes of diabetes mellitus in dogs
  3. Types of diabetes mellitus in dogs
  4. Symptoms of diabetes mellitus in dogs
  5. Diagnosis of diabetes mellitus in dogs
  6. Treatment of diabetes mellitus in dogs
  7. Preventing diabetes mellitus in dogs

What is diabetes mellitus in dogs?

Diabetes mellitus in dogs is an endocrine disease characterized by a state of persistent hyperglycemia, i.e. high blood glucose levels. It is a term given to a range of disorders which create a deficiency in insulin production or by factors that prevent its action. To better understand how this disease develops, we will briefly explain its pathogenesis.

Insulin is a hormone secreted by the pancreas in response to the presence of glucose in the blood. When blood glucose levels rise, the pancreas releases insulin to allow glucose to enter cells and be used for energy. When there is a deficiency in the production of insulin or there are factors that prevent its action, glucose accumulates in the blood producing a state of hyperglycemia.

When the blood glucose concentration exceeds the renal threshold (i.e. the point after which the kidneys can no longer process it), glucose is excreted in the urine (glycosuria). At the same time, the absolute or relative lack of insulin means the tissues have limited access to glucose. Consequently, they need to break down the body's protein and fat reserves to obtain the energy they need.

Learn more about canine blood-glucose levels with our article on the normal blood glucose levels of dogs.

Causes of diabetes mellitus in dogs

Diabetes is usually a multifactorial disease, meaning it is usually a process conditioned by various factors. The specific causes of diabetes mellitus in dogs can be primary or secondary.

  • Primary causes: those that affect the pancreas itself. Diseases which can affect this organ include pancreatitis, exocrine pancreatic insufficiency and immune-mediated insulitis, among others. Learn more with our guide to exocrine pancreatic insufficiency in dogs.

  • Secondary causes: those that do not directly affect the pancreas, such as glucocorticoid treatment, high levels of progesterone, obesity, chronic infections or inflammation and azotemia. Our article on the causes and consequences of obesity in dogs will help us to understand how to avoid this problem.

Types of diabetes mellitus in dogs

In dogs, three distinct types of diabetes mellitus are recognized:

  • Type I diabetes mellitus: also known as insulin-dependent diabetes. It is the most common form of diabetes mellitus in dogs. It occurs as a result of a primary injury to the pancreas that destroys the pancreatic cells responsible for insulin synthesis. As a consequence, there is an absolute deficiency of insulin in the body. This type of diabetes is irreversible, meaning patients require lifelong insulin treatment.

  • Type II diabetes mellitus: also known as non-insulin-dependent diabetes. Although it can occur in dogs, it is more common in cats. In this case, individuals are capable of producing insulin, but there are factors (obesity being one of the most common) that induce insulin resistance in the tissues. In turn, this prevents the hormone from exerting its effect. The advantage of this type of diabetes is that it is reversible.

  • Type III or secondary diabetes mellitus: is a type of diabetes that occurs when certain diseases (such as pancreatitis, Cushing's syndrome in dogs and acromegaly) are combined with certain drugs (such as glucocorticoids or progestins).

Generally speaking, diabetes is not as common in dogs as it is in human beings. According to the most up-to-date reports, diabetes affects around 8.2% of the US human population, whereas only around 1.5% of dogs are likely to develop diabetes[1][2]. It is more common in older and female dogs, although there is also a breed disposition. For example, Samoyed dogs are the most susceptible to diabetes, whereas Boxer dogs are much less likely.

Diabetes Mellitus in Dogs - Symptoms and Treatment - Types of diabetes mellitus in dogs

Symptoms of diabetes mellitus in dogs

The symptoms associated with diabetes mellitus in dogs are usually fairly self-evident. This allows caregivers to more easily detect the signs and go to the veterinarian in the early stages of the disease. The clinical picture of diabetic dogs is characterized by ‘the three P's’: polyuria, polydipsia and polyphagia and weight loss. We explain these clinical signs in more detail below.

  • Polyuria: increased volume of urine. As we explained earlier, when the blood glucose level exceeds the renal threshold, glucose is eliminated through the urine. Glucose acts as an osmotic diuretic, drawing large amounts of water as it passes through the digestive system and increasing the volume of urine.

  • Polydipsia: increased water intake. Polyuria produced by the presence of glucose in the urine gives rise to compensatory polydipsia in order to prevent dehydration of the animal. Since senior dogs are more likely to develop diabetes, it may be the reason your older dog is drinking more water.

  • Polyphagia: increased appetite. As the tissues are not capable of receiving glucose, a negative energy balance is produced that the animal tries to compensate by increasing food consumption.

  • Weight loss: in addition to the three Ps, the lack of intracellular glucose leads the body to break down fat and protein stores for energy, resulting in weight loss.

Diabetes can also lead to a series of complications as a result of long-term hyperglycemia. The main complications associated with diabetes mellitus in dogs are:

  • Cataracts: opacity of the lens. It is the most common complication of diabetes mellitus in dogs. They are irreversible and can evolve rapidly. Learn about other possible causes of this condition with our article on why a dog has cloudy eyes.

  • Bacterial infections: oral, skin and urinary tract infections are very common in diabetic dogs.

  • Hepatic lipidosis: accumulation of fat in the liver that occurs as a result of the mobilization of reserves for energy. It is also known as fatty liver disease in dogs.

  • Pancreatitis: although pancreatitis in dogs is a cause of diabetes, it can also be a complication. This is due to the mobilization of fat reserves which gives rise to a state of hyperlipemia that can predispose to the appearance of acute pancreatitis.

  • Peripheral neuropathy: although it is more frequent in felines, it can also occur in diabetic dogs.

  • Glomerulopathies: this is a group of diseases that lead to a loss of the glomerular filtration membrane and its integrity.

  • Diabetic ketoacidosis: the most serious complication of diabetes mellitus. If not treated quickly, an absolute deficiency of insulin can lead to the death of the dog.
Diabetes Mellitus in Dogs - Symptoms and Treatment - Symptoms of diabetes mellitus in dogs

Diagnosis of diabetes mellitus in dogs

The diagnostic plan for diabetes mellitus in dogs is based on the following factors:

  • Clinical history: as we have mentioned, the most common signs of diabetes in dogs are polyuria, polydipsia, polyphagia and weight loss. If these symptoms present, they need to be reported to the veterinarian in as much detail as possible.

  • Blood tests: hyperglycemia (>200 mg/dl) is detected in all diabetic animals. When the blood-glucose levels are at (180-200 mg/dl), the animal is considered to be prediabetic. In prediabetic or potentially diabetic animals, it is recommended to measure the levels of glycated proteins (fructosamine and glycated hemoglobin) that indicate glycaemia in recent weeks. In addition to hyperglycemia, hyperlipidemic fasting plasma, as well as increased liver enzymes GPT and alkaline phosphatase, can be seen in many diabetic patients.

  • Urinalysis: when the renal threshold is exceeded, glucose will be detected in the urine (glycosuria). Although the animal has polyuria (increased urine volume), urine density is normal or even increased due to the presence of glucose in the urine increasing its osmolarity. In addition, ketonuria (presence of ketone bodies in the urine) and proteinuria (presence of protein in the urine) may be observed in some patients.

  • Imaging diagnosis: given the large number of complications that can develop in diabetic patients, it is advisable to perform imaging tests (mainly X-rays and ultrasound) to detect these complications early.

Find out some general information about diagnostic testing in canines with our article on how to understand a dog's blood test.

Treatment of diabetes mellitus in dogs

Diabetes mellitus is a chronic disease for which there is no curative treatment. Treatment requires proper management of blood-glucose levels to ensure diabetic dogs live with a good quality of life. It is essential to diagnose and control the disease as soon as possible, to reduce or eliminate clinical signs and delay the onset of complications.

It is also essential that caregivers of diabetic dogs understand the function of the disease, its risks and its treatment. It will be their administration of treatment which will control the pathology. The involvement of caregivers is one of the most important factors determining the success or failure of treatment. Neglect of proper treatment management can result in the death of the animal.

The treatment of diabetic dogs is based on four fundamental factors:

  • Insulin: diabetic dogs require lifelong insulin treatment. Unlike in human medicine, insulin cannot be replaced by any other compound. There are several types of insulin depending on their potency and the duration of their effect. In dogs, the first option is Caninsulin, a slow-acting insulin of porcine origin and structurally identical to canine insulin. It is administered subcutaneously (i.e. the dog is given a shot under the skin) 2 times a day. To administer the dose, it is essential to use specific insulin syringes for veterinary medicine, since syringes for human medicine can lead to serious issues such as injection-site infections. Learn more with our guide to insulin for dogs with diabetes.

  • Diet and regular exercise: diabetic dogs must have a special diet that helps to both maintain a correct weight and reduce postprandial hypoglycemia. This requires a diet low in fat (<15% fat), high in fiber (15-22% fiber) and with normal protein levels (20% protein). Ideally the dog should have 2 meals a day and use a specific feed for diabetic dogs. It should be noted that food should always be given before administering an insulin show. The insulin dose should be adjusted according to what the animal eats. For example, if they only eat half of the ration, only half of the insulin dose should be administered.

  • Control of other diseases and concurrent processes: any pathological or even physiological process (such as heat cycle or pregnancy) can cause a diabetic patient to decompensate as these phenomena can produce insulin resistance. It is important to detect and treat these processes in time to keep diabetes under control.

  • Regulation of treatment: the treatment of diabetes mellitus is dynamic and requires adjustment of the insulin dose throughout the life of the animal. For this reason, diabetic patients must attend regular check-ups in which a glycaemia curve will be performed. Weight, polyuria, polydipsia and polyphagia will be monitored. Their insulin dose will be adjusted according to the results.
Diabetes Mellitus in Dogs - Symptoms and Treatment - Treatment of diabetes mellitus in dogs

Preventing diabetes mellitus in dogs

The prevention of diabetes mellitus in dogs is not simple. In most cases, the pathology is caused by processes that cannot be avoided. Despite this, there are certain risk factors that must be taken into account to prevent the onset of diabetes mellitus as much as possible:

  • Neutering: high levels of progesterone can lead to insulin resistance. For this reason, spaying is especially recommended in female dogs as a preventive measure for diabetes mellitus. In addition, in bitches in which the disease has already been diagnosed, spaying can reverse diabetes. Our article on what to expect after a dog is neutered will show other benefits.

  • Obesity: preventing obesity through a balanced diet and regular physical exercise will prevent some of the causes of diabetes, such as pancreatitis.

  • Periodic veterinary check-ups: through these check-ups, prediabetic animals that require specific management can be detected to prevent diabetes from finally developing. These reviews are especially recommended in breeds predisposed to diabetes mellitus such as the Samoyed, Poodle, Dachshund, Schnauzer, Golden Retriever and different types of Terrier.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Diabetes Mellitus in Dogs - Symptoms and Treatment, we recommend you visit our Other health problems category.


1. Center for Disease Control and Prevention. (2022). National Diabetes Statistics Report. Retrieved from:

2. Short, A. D., Catchpole, B., Kennedy, L. J., Barnes, A., Fretwell, N., Jones, C., Thomson, W., & Ollier, W. E. (2007). Analysis of candidate susceptibility genes in canine diabetes. The Journal of Heredity, 98(5), 518–525.

  • Hardy, R. M. (1988). Diabetes mellitus in dogs and cats. AVEPA Magazine, 8(2), 71-88.
  • Marca, M. C., & Loste, A. Canine and feline diabetes mellitus: difficulties in its treatment and control. Argus, 9-15.
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Diabetes Mellitus in Dogs - Symptoms and Treatment