Table 3.

Risk of adverse breast cancer outcomes by diabetes treatment among women diagnosed with stage I/II breast cancer, 2007–2011

All womenSBCERecurrenceBreast cancer death
Ever use after breastN = 14,766n = 791n = 627n = 237
cancer diagnosisn (%)an (%)aHRb (95% CI)n (%)aHRb (95% CI)n (%)aHRb (95% CI)
Metformin
 No12,208 (82.7)661 (83.6)Reference524 (83.6)Reference205 (86.5)Reference
 Yes2,558 (17.3)130 (16.4)0.72 (0.57–0.92)103 (16.4)0.69 (0.53–0.90)32 (13.5)0.51 (0.33–0.78)
Sulfonylureas
 No13,065 (88.5)678 (85.7)Reference535 (85.3)Reference191 (80.6)Reference
 Yes1,701 (11.5)113 (14.3)1.04 (0.81–1.33)92 (14.7)1.07 (0.81–1.40)46 (19.4)1.49 (1.00–2.23)
Insulin
 No13,667 (92.6)703 (88.9)Reference552 (88.0)Reference199 (84.0)Reference
 Yes1,099 (7.4)88 (11.1)1.17 (0.88–1.56)75 (12.0)1.28 (0.94–1.75)38 (16.0)2.58 (1.72–3.90)
Other diabetes treatment
 No13,533 (91.6)713 (90.1)Reference570 (90.9)Reference215 (90.7)Reference
 Yes1,233 (8.4)78 (9.9)0.80 (0.60–1.07)57 (9.1)0.72 (0.51–1.00)22 (9.3)0.75 (0.46–1.21)
  • aEver use was defined as having at least one prescription of a given drug after diagnosis for the purpose of presenting number of users, but the Cox models defined ever use as a time-varying exposure such that at risk time before one becomes a user contributes to the nonuser category.

  • bHRs were adjusted for age at diagnosis, year of diagnosis, AJCC stage, ER/PR status, receipt of complete first course treatment (yes vs. no), receipt of any chemotherapy (yes vs. no), use of adjuvant hormone treatment (time-varying), hypertension, and diabetes.