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Related diseases

Other diseases that may contribute to the development of feline diabetes include:

  • Acromegaly
  • Exocrine pancreatic insufficiency
  • Hyperthyroidism
  • Pancreatitis


Acromegaly is a rare endocrine disease caused by excessive secretion of growth hormone by the pituitary gland. In cats, acromegaly results from a pituitary tumor that secretes the excess growth hormone.

Acromegaly is characterized by chronic overgrowth of connective tissue, bone, and viscera. Clinical signs of acromegaly in cats include:

  • Insulin-resistant diabetes
  • Enlargement of soft tissue organs
  • Proliferation of gum tissue

Radiation therapy appears to be the most effective treatment for feline pituitary tumors.

Exocrine pancreatic insufficiency (EPI)

EPI is a congenital or acquired condition that can affect both dogs and cats, although it is more common in dogs. In cats, EPI typically manifests as the final stage of pancreatitis. EPI may occur concurrently with diabetes mellitus if both the exocrine and endocrine pancreas are damaged.

EPI pathophysiology

  • Digestive enzymes are not secreted normally by the pancreas.
  • Food is not sufficiently digested and processed.
  • Diarrhea and weight loss occur despite normal or increased appetite.

EPI diagnosis and treatment

EPI is diagnosed based on blood tests and is managed with pancreatic enzyme replacements and dietary management, which usually improve clinical signs. However, if EPI results from chronic pancreatitis accompanied by diabetes mellitus, it can be more difficult to treat.

Feline hyperthyroidism

Hyperthyroidism is the most common endocrine (hormone) disorder affecting cats. It creates a wide range of clinical signs resulting from the overproduction of thyroid hormone made by the thyroid gland. This condition often presents concurrently with diabetes mellitus.

Common clinical signs of hyperthyroidism include:

  • Weight loss
  • Polyphagia
  • Polyuria
  • Polydipsia
  • Vomiting
  • Diarrhea
  • Hyperactivity
  • Matted or greasy haircoat

Over time excessive thyroid hormones can cause heart disease and cats may exhibit:

  • Heart murmur
  • Difficulty breathing
  • Tachycardia
  • Arrhythmias

Diagnosis of feline hyperthyroidism

In most cats, laboratory measurement of thyroid hormone T4 will confirm the presence of hyperthyroidism. A small percentage of cats with hyperthyroidism will show normal T4 levels. In these cases, if you still suspect a cat has hyperthyroidism, conduct:

  • Follow-up total T4 measurement 3 or more weeks later
  • Free T4 measurement (by equilibrium dialysis)
  • T3 suppression test

Treatment of feline hyperthyroidism

After you have confirmed a hyperthyroidism diagnosis, 4 treatment options exist including:

  • Surgical thyroidectomy
  • Radioactive-iodine therapy
  • Anti-thyroid medications
  • Low iodine thyroid diet


Pancreatitis or inflammation of the pancreas causes digestive enzymes to leak into and damage the surrounding pancreatic tissues. In most cases, the cause of pancreatitis is idiopathic; however, risk factors include:

  • High-fat, low-protein diet
  • Breed—Siamese cats are at higher risk
  • Cholangiohepatitis
  • Toxoplasmosis
  • Feline leukemia virus
  • Feline herpesvirus
  • Obesity
  • Diabetes mellitus
  • Cushing's disease
  • Chronic renal failure
  • Neoplasia

Acute pancreatitis or pancreatic neoplasia may produce temporary diabetes mellitus. If extensive pancreatic necrosis occurs, diabetes may become a permanent condition.