1. Look for the Characteristic Symptoms of Glucagonoma
Glucagonoma is a pancreatic tumor of the pancreas' islet cells. In up to 80% of all cases, this type of pancreatic tumor is malignant (cancerous). The islet cells of the pancreas produce the hormones insulin and glucagon. If a patient has a glucagonoma, their pancreas will produce too much insulin and glucagon. One of the first things that a doctor will do in trying to diagnose glucagonoma is to look for the physical symptoms of this condition. Patients with glucagonoma will exhibit a characteristic skin rash called necrolytic migratory erythema. This rash appears on one's chest, stomach, buttocks, arms and legs. The rash typically has a brownish or reddish color, and it may have a scale-like or crusty appearance. The rash can also contain pus or fluid filled lesions. Other physical symptoms of glucagonoma include a bright and inflamed tongue or mouth, increased thirst, increased urination, weight loss and an increased appetite. If a doctor sees these symptoms in a patient, further diagnostic testing will often follow.
2. Measure Glucagon Levels in the Blood
Patients with glucagonoma will exhibit higher than normal blood serum glucagon levels. To test one's serum glucagon, a doctor, nurse or phlebotomist will draw a sample of the patient's blood, and a laboratory will test that sample for glucagon. Normal serum glucagon levels in an adult range from 50 to 100 pg/mL (picograms per milliliter). Patients with glucagonoma will have serum glucagon levels above 100 pg/mL.
3. Determine the Fasting Blood Glucose Level
Another part of the diagnosis of glucagonoma is testing one's fasting blood glucose level. Because of the elevated insulin and glucagon levels in patients with glucagonoma, these patients will also experience a higher than normal fasting blood glucose. To test one's fasting blood glucose, a patient does not eat for 6 hours prior to the test. The patient then has a blood sample drawn, and a laboratory determines the fasting blood glucose level. A fasting blood glucose level up to 100 mg/dL (milligrams per deciliter) is a normal result. Patients with glucagonoma will have a fasting blood glucose level over 100 mg/dL.
4. Use the Glucose Tolerance Test
The glucose tolerance test can also aid in the diagnosis of glucagonoma. For this particular test, a patient drinks a sugary liquid given to them by their doctor. A laboratory will then test the patient's blood glucose every hour for 3 hours following the consumption of the sugary liquid. In many cases, the patient will also have their fasting blood glucose level determined prior to the start of the glucose tolerance test. Patients with glucagonoma will exhibit higher than normal blood glucose levels during the glucose tolerance test. Normal blood glucose levels for this test depend on the amount of glucose in the sugary drink consumed by the patient.
5. Look for a Tumor in the Pancreas Using Imaging Techniques
Because a glucagonoma is a pancreatic tumor, to definitively diagnose glucagonoma, a doctor will need to visualize a pancreatic tumor in the patient. A doctor can use various imaging techniques, such as a CT (computerized tomography) scan or MRI (magnetic resonance imaging) to visualize a pancreatic tumor.
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