title: Mortality after cancer among patients with diabetes mellitus: effect of diabetes duration and treatment.
abstract: OBJECTIVE
  The prognostic role of different diabetes treatment types has not been studied in detail. We compared mortality rates among cancer patients with and without diabetes, accounting for diabetes treatment and diabetes duration.
  
  
  METHODS
  This register-based study included all cancer patients diagnosed in Denmark during 1995-2009. The patients were classified into four groups according to diabetes status at the time of cancer diagnosis: no diabetes, diabetes without medication, diabetes with only oral hypoglycaemic agent (OHA) or diabetes with insulin treatment. Poisson models were used to examine the association between pre-existing diabetes in cancer patients and mortality relative to the non-diabetic cancer population.
  
  
  RESULTS
  Among 426,129 patients with incident cancer, we identified 42,205 patients with diabetes prior to cancer diagnosis. Overall, cancer patients with diabetes had higher mortality rates than non-diabetic cancer patients, highest among OHA- or insulin-treated patients. For all cancers combined and diabetes duration of 2 years at cancer diagnosis, insulin-treated patients experienced the highest mortality rate ratios starting from 3.7 (95% CI 2.7, 5.1) for men and 4.4 (3.1, 6.5) for women 1 year after cancer diagnosis, increasing to 5 (3.5, 7.0) for men and 6.5 (4.2, 9.3) for women 9 years after cancer diagnosis.
  
  
  CONCLUSIONS
  Our study provides strong evidence that cancer patients with pre-existing diabetes experience higher mortality than cancer patients without diabetes. The higher mortality seen among cancer patients treated with OHAs or insulin is in accordance with the existing evidence that more intensive diabetes treatment reflects a larger degree of comorbidity at the time of cancer diagnosis, and hence poorer survival.
authors.affiliation: Steno Diabetes Center, 2820, Gentofte, Denmark, ksrc@sund.ku.dk.
authors.forename: Kristina
authors.initials: K
authors.lastname: Ranc
authors.forename: Marit E
authors.initials: ME
authors.lastname: Jørgensen
authors.forename: Søren
authors.initials: S
authors.lastname: Friis
authors.forename: Bendix
authors.initials: B
authors.lastname: Carstensen
mesh_terms: D000368:Aged; D015897:Comorbidity; D003718:Denmark; D048909:Diabetes Complications / Q000401:mortality*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000401:mortality*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications* / Q000401:mortality*; D016012:Poisson Distribution; D011379:Prognosis; D016016:Proportional Hazards Models; D012042:Registries; D016896:Treatment Outcome
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin