title: Diabetes and pancreatic cancer: chicken or egg?
abstract: OBJECTIVE
  Although half of all patients with pancreatic cancer are diabetic at the time of diagnosis, it remains unclear whether the diabetes associated with pancreatic cancer is a cause or an effect of the malignancy.
  
  
  METHODS
  Epidemiologic studies were reviewed, the geographic prevalence of diabetes and the incidence of pancreatic cancer were examined, and clinical and laboratory studies were reviewed.
  
  
  RESULTS
  Long-standing diabetes increases the risk of pancreatic cancer by 40% to 100%, and recent-onset diabetes is associated with a 4- to 7-fold increase in risk, such that 1% to 2% of patients with recent-onset diabetes will develop pancreatic cancer within 3 years. Treatment of diabetes or morbid obesity decreases the risk of pancreatic cancer, and metformin therapy decreases the risk due to both its antidiabetic and antineoplastic effects. Recent-onset diabetes associated with pancreatic cancer likely represents secondary or type 3 diabetes. The discrimination of type 3 diabetes from the more prevalent type 2 diabetes may identify the high-risk subgroup of diabetic patients in whom potentially curable pancreatic cancer may be found.
  
  
  CONCLUSIONS
  Type 2 and type 1 diabetes mellitus increase the risk of pancreatic cancer with a latency period of more than 5 years. Type 3 diabetes mellitus is an effect, and therefore a harbinger, of pancreatic cancer in at least 30% of patients.
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Johns Hopkins Bayview Medical Center, Baltimore, MD, USA.
authors.forename: J Trent
authors.initials: JT
authors.lastname: Magruder
authors.forename: Dariush
authors.initials: D
authors.lastname: Elahi
authors.forename: Dana K
authors.initials: DK
authors.lastname: Andersen
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood; D016022:Case-Control Studies; D015984:Causality; D048909:Diabetes Complications / Q000453:epidemiology / Q000209:etiology*; D003920:Diabetes Mellitus / Q000628:therapy; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D058228:Islet Amyloid Polypeptide / Q000097:blood; D008297:Male; D008687:Metformin / Q000627:therapeutic use; D010190:Pancreatic Neoplasms / Q000150:complications* / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D014408:Biomarkers, Tumor; D058228:Islet Amyloid Polypeptide; D008687:Metformin; D005947:Glucose