C-peptide (oral glucose tolerance test) with pancreatic elastase-1 (pancreatic function screening)

Why This Test Is Done

Your doctor may recommend this test if you have symptoms of diabetes (like frequent urination, extreme thirst, or fatigue), unexplained weight loss, or digestive problems. It’s also used to check pancreatic health in people with chronic pancreatitis or suspected pancreatic disorders. Sometimes, it’s part of an oral glucose tolerance test to monitor how your body responds to sugar.

What to Expect Before the Test

You’ll fast overnight (usually 8–12 hours) before the test. On the day of the test, you’ll drink a sugary liquid (glucose solution) to simulate eating. Blood samples will be taken before drinking the solution and at intervals afterward to measure C-peptide and pancreatic elastase-1 levels.

Blood samples are drawn from a vein (usually in your arm) at specific times. The test involves multiple draws to track how your body processes sugar and produces digestive enzymes over time. The results help assess how effectively your pancreas functions.

You may feel slightly dizzy or lightheaded after drinking the sugary liquid due to the quick sugar intake. Drink plenty of water afterward to stay hydrated. Avoid driving or operating heavy machinery until you feel steady.

Your results will compare C-peptide levels and pancreatic elastase-1 over time to your baseline. Low C-peptide or abnormal elastase-1 levels may indicate diabetes, pancreatic insufficiency, or other digestive issues. Your doctor will interpret these results in the context of your symptoms and medical history.

This test helps doctors diagnose diabetes, assess pancreatic function, and monitor conditions like chronic pancreatitis or celiac disease. It also supports treatment planning for people with suspected insulin resistance or digestive disorders.