Table 2.

Estimates of lung cancer risk associated with metformin use

Metformin useNumber of eventsPerson-yearsAdjusteda HR (95% CI)
Never464257,542.421.00 (reference)
Ever283171,015.061.02 (0.85–1.22)
 Total duration, y
  <2.010061,047.001.02 (0.81–1.28)
  2.0–4.99356,423.331.00 (0.78–1.28)
  ≥5.09053,544.731.04 (0.78–1.37)
 Recency of use
  Former7533,496.721.19 (0.89–1.58)
  Recent3721,484.371.07 (0.75–1.52)
  Current
   <5.0 years10775,365.200.93 (0.74–1.17)
   ≥5.0 years6440,668.761.04 (0.76–1.42)
 Cumulative dose (mg), quartiles
  ≤750,0009155,360.211.00 (0.79–1.27)
  750,001–2,300,0008452,118.330.98 (0.76–1.27)
  2,300,001–4,930,0006741,097.811.04 (0.77–1.39)
  >4,930,0004122,438.701.21 (0.83–1.77)
  • aStratified on age and adjusted for gender, race/ethnicity, birth year, diabetes duration, BMI, alcohol use, Charlson comorbidity index, smoking history (status and pack-years), education, income level, creatinine level, HbA1c level, and use of other diabetes medications.