Simple Summary: The early detection of pancreatic cancer is critical as it is usually too late for potentially curative surgical resection when obvious symptoms such as jaundice have developed. The pancreas has two main functions in the body, namely, an endocrine role, where it produces insulin to control blood glucose levels; and an exocrine role, where it produces enzymes that aid digestion. Impairment of this latter role is known as pancreatic exocrine insufficiency (PEI). It is an established feature of advanced pancreatic cancer, but it is unclear whether it is present in the early stages when surgery may still be an option. This study used two validated methods of testing pancreatic exocrine function, a breath test and a stool test, to demonstrate that exocrine insufficiency is associated with resectable pancreatic cancer. Pancreatic ductal adenocarcinoma (PDAC) is usually diagnosed late, leading to a high mortality rate. Early detection facilitates better treatment options. The aim of this UK-based case–control study was to determine whether two validated tests for pancreatic exocrine insufficiency (PEI), namely, the 13C-mixed triglyceride breath test (13C-MTGBT) and a faecal elastase (FE-1) test, can discriminate between patients with resectable PDAC versus healthy volunteers (HVs) along with a comparison group with chronic pancreatitis (CP). Discrimination between disease states and HVs was tested with receiver operator characteristic (ROC) curves. In total, 59 participants (23 PDAC (16 men), 24 HVs (13 men) and 12 CP (10 men)) were recruited, with a similar age in each population, and a combined median (IQR) age of 66 (57–71). The areas under the ROC curve for discriminating between PDAC and HVs were 0.83 (95% CI: 0.70–0.96) for the 13C-MTGBT, and 0.85 (95% CI: 0.75–0.95) for the FE-1 test. These were similar to CP vs. HV. In conclusion, PEI occurs in resectable PDAC to a similar extent as in CP; further large-scale, prospective studies using these tests in the primary care setting on high-risk groups are warranted. [ABSTRACT FROM AUTHOR]