Insulinomas are rare and can be difficult to diagnose. Some data show the average time from the start of symptoms to diagnosis is about a year and a half.
If your healthcare provider thinks you have an insulinoma, you may stay in the hospital for a few days. This is so your healthcare provider can watch your blood sugar and other substances in your blood while you fast. You will not be able to eat or drink anything except water during this time. If you have an insulinoma, you will probably have very low blood sugar levels within 48 hours of starting this test. If your symptoms of low blood sugar have been after meals, you may have a test of your blood sugar and insulin for several hours after a meal.
You may also have imaging tests. These can help find out how big your tumor is and where it's located. A transabdominal ultrasound study is usually the first test done. Other tests include endoscopic ultrasound, CT scan or MRI. If the insulinoma is too small to be seen with these imaging tests, you may need tests that sample blood from multiple areas of your pancreas. These will find where the extra insulin is being released into your bloodstream.