Medical Jargon Explained: Hypo- versus Hyperglycemia

Endocrine glands: Pancreas

The pancreas, an organ located near your dog’s stomach and small intestine, has two separate functions. It produces digestive enzymes and a number of important hormones, including insulin and glucagon, which control glucose levels in the blood.  This hormone production makes the pancreas a part of your dog’s endocrine system.


Glucose is a form of sugar. Your dog’s digestive system converts food, primarily carbohydrates, into glucose. Glucose then circulates in the bloodstream and serves as the main source of energy for your dog's body.  Some parts of your dog’s body, like the brain and red blood cells, are completely dependent on glucose as an energy source.


After a meal, blood glucose levels rise. Because not all of the glucose is needed immediately, the excess is converted to glycogen that is stored in the liver and muscles so it can be used later when blood sugar levels drop again. This system ensures that glucose levels stay relatively constant in the bloodstream.


Insulin is a hormone released in response to an increase in blood glucose levels.  It helps transport glucose out of the bloodstream and into cells where it can be used for energy or converted to glycogen.


Glucagon is a hormone that has the opposite effect of insulin. When blood glucose levels fall glucagon stimulates the liver to convert stored glycogen back into glucose and to secrete it into the bloodstream. This helps prevent hypoglycemia between meals.

Hypoglycemia versus Hyperglycemia

Disturbances in blood glucose levels are a serious health threat for your dog.


When your dog's blood glucose levels drop below normal it is referred to as hypoglycemia.

Hypoglycemia can have a number of causes and vary in severity. Don't dismiss the symptoms of mild hypoglycemia.  Quick action can save your dog's life. Severe hypoglycemia is a life-threatening emergency.

Puppies are particularly prone to developing hypoglycemia, but adult dogs can become hypoglycemic also. Some of the causes of hypoglycemia in dogs are:
  • insufficient food intake, particularly if puppies are not fed frequently enough
  • strenuous exercise
  • insulin overdose in diabetic dogs
  • Addison's disease
  • insulin-producing pancreatic tumors
  • liver disease
  • bacterial infections of the blood
The severity of the symptoms depends on how low and how rapidly glucose levels drop. In severe cases it can result in brain damage and death. Some of the clinical signs of hypoglycemia are:
  • listlessness
  • lethargy
  • depression
  • loss of appetite
  • trembling and twitching
  • glassy eyes and dilated pupils
  •  poor coordination/bizarre behavior
  • weakness
  • collapse
  • seizures
  • coma
First aid for hypoglycemia is aimed at quickly increasing blood glucose levels. If your dog can eat and swallow, feed him immediately. If he cannot swallow, rub honey, Karo Syrup, or a dissolved sugar solution onto his gums and rush him to the nearest veterinary hospital.

Note that low blood sugar levels can also lead to hypothermia. Make sure you keep your dog warm.

It is important to find out what caused the hypoglycemia in the first place. Your vet will look for any underlying diseases and may recommend changes to your dog’s diet, exercise routine or medication dosages.

Hyperglycemia/Diabetes Mellitus

When your dog has excess glucose in the blood it is referred to as hyperglycemia. Hyperglycemia is the hallmark of diabetes mellitus, but there can also be other causes, including stress.

Diabetes is a common hormonal disorder in dogs. It is caused either by insufficient production of insulin by the pancreas or by the body's inability to respond to it. The vast majority of dogs develop what is called Type 1 or insulin-dependent diabetes, meaning that the pancreas has stopped producing and secreting adequate amounts of insulin.

Symptoms of diabetes mellitus include:
  • excessive drinking
  • frequent urination
  • increased appetite
  • weight loss
  • weakness
  • changes in behavior
Veterinarians will often diagnose diabetes based on a dog’s clinical signs, a physical examination, blood work, and a urinalysis.  Dietary changes and twice daily insulin injections are usually necessary to successfully manage cases of canine diabetes. Severely affected dogs may require hospitalization before they are stable enough to go home. Diabetes cannot be cured, but with a dedicated owner and close monitoring, successful management is usually possible.

Left untreated, diabetes can lead to serious complications including:
  • recurrent infections
  • cataracts and blindness – although even the most well-regulated diabetic dogs usually develop cataracts eventually
  • diabetic ketoacidosis – a potentially fatal condition if not treated rapidly and aggressively
  • nervous system disorders
  • pancreatitis
  • kidney disease
This is one of the reasons why annual check-up by your vet is such a good idea. If you have a senior dog, you might want to visit your vet every six months for routine urine and blood screens. Early detection gives your dog a better chance for successful treatment.

If your dog is showing any symptoms listed above, visit your vet immediately.