Table 1

Baseline characteristics and results of Cox regression analysis for incidence of cancer among metformin users and comparators

Metformin usersComparatorsDiagnosed cancerUnadjustedAdjusted*
Comparators4,0854741.001.00
Metformin users4,0852970.46 (0.40–0.53)0.63 (0.53–0.75)
Sex
    Female1,848 (45.9)1,875 (45.2)3151.001.00
    Male2,237 (54.1)2,210 (54.8)4561.26 (1.09–1.45)1.37 (1.18–1.59)
Age (years)
    35–551,001 (24.5)533 (13.1)511.001.00
    56–63964 (23.6)647 (15.8)1382.72 (1.97–3.75)2.66 (1.92–3.68)
    64–69865 (21.2)691 (16.9)1603.40 (2.48–4.67)3.13 (2.27–4.32)
    70–76781 (19.1)939 (23.0)2054.61 (3.39–6.28)4.09 (2.98–5.61)
    77–100474 (11.6)1,275 (31.2)2175.95 (4.37–8.12)4.86 (3.51–6.73)
Smoking status
    Current577 (14.1)558 (13.7)1091.001.00
    Ex-smoker1,015 (24.9)866 (21.2)1770.99 (0.78–1.26)0.77 (0.60–0.98)
    Never1,637 (40.1)1,411 (34.5)2710.87 (0.69–1.09)0.75 (0.60–0.94)
    Not known856 (21.0)1,250 (30.6)2141.19 (0.94–1.51)0.91 (0.72–1.16)
Carstairs deprivation category
    1 (least deprived)224 (5.5)206 (5.0)461.001.00
    2805 (19.7)902 (22.1)1620.75 (0.56–1.01)0.74 (0.55–0.99)
    31,129 (27.6)1,171 (28.7)2230.80 (0.61–1.07)0.82 (0.62–1.09)
    4458 (11.2)488 (12.0)990.78 (0.56–1.08)0.81 (0.58–1.12)
    5521 (12.8)457 (11.2)770.66 (0.47–0.92)0.69 (0.49–0.97)
    6603 (14.8)579 (14.2)1060.71 (0.52–0.98)0.79 (0.58–1.09)
    7 (most deprived)345 (8.5)282 (6.9)580.72 (0.50–1.04)0.83 (0.58–1.19)
BMI30.7 ± 3.528.6 ± 3.10.93 (0.91–0.95)0.98 (0.96–1.00)
A1C (%)7.9 ± 1.07.2 ± 1.20.77 (0.72–0.82)0.91 (0.84–0.98)
Insulin use
    No use3,833 (93.8)3,512 (86.0)6961.001.00
    Use within 1 year252 (6.2)573 (14.0)750.99 (0.85–1.15)1.13 (0.97–1.33)
Sulphonylurea use
    No use2,196 (53.8)1,996 (73.3)4831.001.00
    Use within 3 months1,889 (46.2)1,089 (26.7)2881.00 (0.78–1.28)1.12 (0.87–1.47)
  • Data are n, n (%), means ± SD, or HR (95% CI).

  • *Adjusted for all covariates.