What Is Insulinoma?
Insulinoma is a tumor of the pancreatic beta cells that produces too much insulin. Excess insulin drives blood glucose dangerously low (hypoglycemia), which starves the brain of fuel and can cause weakness, collapse, or seizures. Middle-aged to older dogs — especially medium and large breeds — are the usual patients; cats are rarely affected.
Unlike dog diabetes, where insulin is lacking and glucose runs high, insulinoma is the opposite problem: too much insulin and glucose that crashes, often after fasting, exercise, or excitement.
Why it matters
Repeated hypoglycemic crises damage the brain and quality of life. Documented low glucose plus an inappropriately high insulin level points clinicians toward this tumor so staging and surgery can be planned.
Signs Owners Notice
- Episodes of weakness, wobbliness, or “staring” that improve after eating
- Tremors, seizures, or collapse
- Hunger, weight gain, or restlessness between episodes
- Signs that cluster in the morning before breakfast or after play
- In advanced cases: lethargy or neurologic deficits that linger
Owners sometimes mistake early episodes for “just getting old” or brief vestibular spells.
Diagnosis and Treatment
Diagnosis pairs documented hypoglycemia with insulin levels that are not appropriately suppressed, plus imaging (ultrasound, CT) to look for a pancreatic nodule and metastasis. Whipple’s triad (symptoms of hypoglycemia, low measured glucose, improvement after glucose rises) guides the workup.
Treatment options may include:
- Emergency glucose support — food, karo/corn syrup on gums if safe, or IV dextrose under veterinary care
- Surgical removal — often the preferred approach when a solitary pancreatic mass is found and staging is favorable
- Medical management — frequent meals, prednisone, and drugs such as diazoxide when surgery is not possible or metastasis is present
- Oncology follow-up — monitoring for recurrence and discussing adjunct therapies case by case
Do not force syrup into a seizing dog’s mouth — protect the airway and get to an ER.
Practical Tips for US Pet Owners
- Keep a log of episode times, meals, and activity for your vet.
- Ask how to safely give oral glucose gel at home between crises.
- Feed small, frequent meals as directed; avoid long fasts before procedures unless instructed.
- Find internist or surgical referral options via veterinary clinic listings.
- Request copies of insulin/glucose pairs and imaging reports for second opinions.
When to see a vet
Emergency care for seizures, collapse, or inability to stand. Prompt evaluation for recurring weakness that improves after eating, especially in older dogs.
Key Takeaways
- Insulinoma is an insulin-secreting pancreatic tumor that causes hypoglycemia.
- It is the clinical opposite of diabetes: too much insulin, not too little.
- Surgery plus medical support and meal timing are the mainstays of long-term care.
FAQ
Is insulinoma the same as diabetes?
No. Diabetes features high blood sugar from insulin deficiency or resistance; insulinoma features low blood sugar from excess insulin.
Can diet alone cure it?
Frequent meals help stabilize glucose but do not remove the tumor — they bridge to surgery or support medical management.
What is the outlook?
Many dogs improve after mass removal; metastatic disease shortens survival, so staging before surgery matters.