Table 3

Cox proportional hazards regression for incident cancer events: overall and age stratified

Breast cancerColon cancerPancreatic cancerProstrate cancerAny incident cancer
HR95% CIHR95% CIHR95% CIHR95% CIHR95% CI
Overall without dose variables
 Glargine insulin1.04(0.84–1.28)0.75(0.58–0.98)*0.99(0.71–1.39)1.14(0.91–1.43)0.94(0.88–1.01)
 Combination insulin1.07(0.86–1.34)0.92(0.72–1.19)0.75(0.50–1.13)0.88(0.67–1.16)0.93(0.87–1.00)
 Female1.04(0.84–1.30)0.96(0.71–1.31)0.69(0.65–0.73)
 Metformin use1.28(1.05–1.57)*0.94(0.72–1.22)1.25(0.89–1.75)0.97(0.76–1.24)1.01(0.94–1.08)
Overall with dose quartile variables
 Glargine insulin1.03(0.83–1.29)0.79(0.60–1.05)0.95(0.67–1.35)1.12(0.88–1.42)0.94(0.88–1.01)
 Combination insulin1.08(0.86–1.36)0.95(0.74–1.23)0.71(0.47–1.07)0.89(0.68–1.18)0.94(0.87–1.01)
 Female1.05(0.84–1.31)0.96(0.71–1.31)0.69(0.65–0.73)
 Metformin use1.28(1.05–1.57)*0.94(0.72–1.22)1.25(0.89–1.75)0.97(0.76–1.24)1.00(0.94–1.08)
 Daily insulin dose quartile 20.93(0.73–1.19)0.98(0.73–1.31)1.12(0.77–1.63)0.83(0.64–1.10)0.99(0.91–1.06)
 Daily insulin dose quartile 31.00(0.79–1.27)1.22(0.93–1.61)0.96(0.64–1.42)0.98(0.75–1.28)0.98(0.91–1.06)
 Daily insulin dose quartile 40.98(0.76–1.25)1.16(0.87–1.54)0.78(0.51–1.19)0.91(0.68–1.20)1.01(0.94–1.10)
Age stratified with dose quartile variables
 >75 years old
  Glargine insulin0.81(0.59–1.12)0.79(0.55–1.13)1.01(0.65–1.56)0.97(0.7–1.36)0.94(0.85–1.03)
  Combination insulin1.09(0.81–1.46)0.92(0.65–1.29)0.50(0.28–0.91)*0.75(0.5–1.12)0.92(0.83–1.01)
  Female1.23(0.91–1.67)1.07(0.71–1.61)0.66(0.61–0.72)
  Metformin use1.13(0.84–1.52)0.79(0.54–1.15)1.10(0.69–1.76)1.24(0.88–1.75)1.02(0.92–1.12)
  Daily insulin dose quartile 20.72(0.51–1)1.20(0.82–1.75)1.12(0.71–1.78)0.64(0.43–0.96)*0.99(0.89–1.09)
  Daily insulin dose quartile 31.05(0.77–1.43)1.55(1.07–2.23)*0.90(0.55–1.48)1.06(0.74–1.53)1.03(0.93–1.14)
  Daily insulin dose quartile 40.96(0.7–1.33)1.55(1.07–2.25)*0.65(0.37–1.13)1.11(0.77–1.61)1.02(0.91–1.13)
 ≤75 years old
  Glargine insulin1.33(0.97–1.82)0.80(0.53–1.23)0.88(0.48–1.60)1.28(0.91–1.79)0.95(0.85–1.05)
  Combination insulin1.09(0.76–1.55)1.02(0.68–1.52)1.10(0.61–1.98)1.05(0.71–1.54)0.97(0.87–1.08)
  Female0.85(0.61–1.19)0.86(0.53–1.39)0.72(0.66–0.78)
  Metformin use1.43(1.08–1.89)*1.13(0.78–1.63)1.47(0.89–2.42)0.78(0.55–1.10)1.00(0.91–1.10)
  Daily insulin dose quartile 21.22(0.86–1.74)0.74(0.47–1.17)1.18(0.60–2.3)1.01(0.70–1.47)0.98(0.87–1.10)
  Daily insulin dose quartile 30.94(0.65–1.36)0.89(0.59–1.36)1.12(0.58–2.19)0.88(0.59–1.30)0.93(0.83–1.04)
  Daily insulin dose quartile 40.99(0.67–1.45)0.78(0.50–1.22)1.09(0.54–2.19)0.66(0.43–1.04)1.01(0.90–1.14)
  • Reference insulin use is nonglargine only. Race/ethnicity reference group is other than black or Hispanic. Tobacco exposure is defined as a diagnosis of tobacco-related lung disease or diagnosis of tobacco use. We also adjusted for age category, race/ethnicity, diabetes complications, obesity diagnosis, oral estrogen use, Part D low-income subsidy (a poverty indicator), 14 Charlson comorbidities, and tobacco exposure diagnosis. Models including quartile of mean daily dose; the lowest dose quartile is the referent. Mean insulin units per day: 32, 47, 71, and 119 for dose quartiles 1–4, respectively. For overall with and without dose quartile variables: models include all events listed in Table 2. For age-stratified data for those aged >75 years: models include 308 breast, 259 colon, 127 pancreatic, 226 prostate, and 3,003 any cancer cases. For age-stratified data for those aged ≤75 years: models include 245 breast, 169 colon, 77 pancreas, 201 prostate, and 2,463 any cancer cases.

  • *P < 0.05.

  • P < 0.001.