Background: Among the gastrointestinal cancers, pancreatic cancer has the poorest prognosis. It is important to diagnose patients when the pancreatic cancer is still operable, which remains the only effective procedure. The initial manifestations of pancreatic cancer include abnormal glucose tolerance and onset of diabetes. Methods: We experienced a patient with B-cell chronic lymphocytic leukemia (B-CLL) who was diagnosed with pancreatic cancer after progression of diabetes. Results: A 74-year-old man was diagnosed with B-cell chronic lymphocytic leukemia and was followed up at our outpatient department. In March 2011, he suffered from deterioration of diabetes (HgbA1c: 7. 6%) and underwent detailed examination. After examination, patient was diagnosed with Stage IV pancreatic cancer and is treated with gemcitabine monotherapy. Conclusions: The incidence of diabetes and abnormal glucose tolerance complicated with pancreatic cancer is relatively high. It has been shown that diabetes correlates positively with the risk of onset of pancreatic cancer. However, it has also been demonstrated that diabetes is the result rather than the risk factor of pancreatic cancer onset. Although abnormal glucose tolerance and diabetes onset are important as the initial manifestations of pancreatic cancer. It is necessary to diagnose patients in the early stage of pancreatic cancer, when it is still operable. In comparison with the conventional risk factors of smoking and diabetes, a family history of pancreatic cancer and various hereditary syndromes are much superior risk factors. Patients with pancreatic cancer who have at least 2 fi rst-degree relatives are considered to have familial pancreatic cancer.