Diabetic ketoacidosis (DKA) accompanies any other intra-abdominal pathology. Serum amylase/lipase levels are commonly used in order to rule out acute pancreatitis in patients having abdominal pain in DKA. A more specific and noninvasive diagnostic tool - amylase/creatinine clearance ratio (ACCR) - can be used to rule out pancreatitis in patients with DKA. A 14-year-old girl was admitted with abdominal pain and nausea. She had been followed up for type 1 diabetes mellitus for the last 5 years. The serum amylase levels were increased up to 687 U/L (normal: 28-120 U/L) on the third day of hospitalization. Simultaneous serum and urinary amylase concentrations were measured, and ACCR was calculated (1.2%). The diagnosis of pancreatitis was ruled out. The serum amylase levels decreased in the following days, and she was discharged. ACCR determination is a simple and specific test to diagnose pancreatitis, especially in patients with DKA.