Background & Aims: The temporal association between diabetes mellitus and pancreatic cancer is poorly understood. We compared temporal patterns in diabetes prevalence in pancreatic cancer and controls. Methods: We reviewed the medical records of pancreatic cancer cases residing within 120 miles or less of Rochester, Minnesota, seen at the Mayo Clinic between January 15, 1981, and July 9, 2004, and approximately 2 matched controls/case residing locally. We abstracted all outpatient fasting blood glucose (FBG) levels for up to 60 months before index (ie, date of cancer diagnosis for cases) and grouped them into 12-month intervals; 736 cases and 1875 controls had 1 or more outpatient FBG levels in the medical record. Diabetes was defined as any FBG level of 126 mg/dL or greater or treatment for diabetes, and was defined as new onset when criteria for diabetes were first met 24 or fewer months before index, with at least 1 prior FBG level less than 126 mg/dL. Results: A higher proportion of pancreatic cancer cases compared with controls met the criteria for diabetes at any time in the 60 months before index (40.2% vs 19.2%, P < .0001). The proportions were similar in the -60 to -48 (P = .76) and -48 to -36 (P = .06) month time periods; however, a greater proportion of cases than controls met criteria for diabetes in the -36 to -24 (P = .04), -24 to -12 (P < .001), and -12 to 0 (P < .001) month time periods. Diabetes was more often new onset in cases vs controls (52.3% vs 23.6%, P < .0001). Conclusions: Diabetes has a high (40%) prevalence in pancreatic cancer and frequently is new onset. Identification of a specific biomarker for pancreatic cancer-induced diabetes may allow screening for pancreatic cancer in new-onset diabetes.
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