Table 2.

Select patient and disease characteristics by baseline diabetes status and ever use of metformina

Baseline diabetes statusAmong women with diabetes
No (n = 10,222)Yes (n = 4,544)Nonusers (n = 2,287)Users of metformin (n = 2,257)
n (%)n (%)n (%)n (%)
Year of diagnosis
 20072,126 (20.8)747 (16.4)307 (13.4)440 (19.5)
 20082,097 (20.5)824 (18.1)381 (16.7)443 (19.6)
 20092,007 (19.6)928 (20.4)499 (21.8)429 (19.0)
 20101,993 (19.5)951 (20.9)488 (21.3)463 (20.5)
 20111,999 (19.6)1,094 (24.1)612 (26.8)482 (21.4)
Age at diagnosis
 66–704,214 (41.2)1,590 (35.0)721 (31.5)869 (38.5)
 71–753,329 (32.6)1,608 (35.4)794 (34.7)814 (36.1)
 76–802,679 (26.2)1,346 (29.6)772 (33.8)574 (25.4)
Stage at diagnosis
 I6,729 (65.8)2,681 (59.0)1,335 (58.4)1,346 (59.6)
 II3,493 (34.2)1,863 (41.0)952 (41.6)911 (40.4)
Tumor grade
 12,995 (29.3)1,148 (25.3)589 (25.8)559 (24.8)
 24,563 (44.6)1,976 (43.5)959 (41.9)1,017 (45.1)
 32,222 (21.7)1,179 (25.9)607 (26.5)572 (25.3)
 455 (0.5)23 (0.5)10 (0.4)13 (0.6)
 Others/unknown387 (3.8)218 (4.8)122 (5.3)96 (4.3)
Tumor size (in mm)
 1–103,521 (34.4)1,302 (28.7)618 (27.0)684 (30.3)
 11–255,058 (49.5)2,326 (51.2)1,180 (51.6)1,146 (50.8)
 26–501,309 (12.8)759 (16.7)406 (17.8)353 (15.6)
 >50154 (1.5)75 (1.7)36 (1.6)39 (1.7)
 Others/unknown180 (1.8)82 (1.8)47 (2.1)35 (1.6)
Positive lymph nodes
 All negative8,009 (78.4)3,356 (73.9)1,674 (73.2)1,682 (74.5)
 1–31,636 (16.0)869 (19.1)435 (19.0)434 (19.2)
 ≥438 (0.4)16 (0.4)6 (0.3)10 (0.4)
 Others/unknown539 (5.3)303 (6.7)172 (7.5)131 (5.8)
ER/PR status
 ER+/PR+7,208 (70.5)3,205 (70.5)1,632 (71.4)1,573 (69.7)
 ER/PR1,318 (12.9)590 (13.0)285 (12.5)305 (13.5)
 ER+/PR1,208 (11.8)499 (11.0)243 (10.6)256 (11.3)
 ER/PR+70 (0.7)33 (0.7)20 (0.9)13 (0.6)
 Unknown418 (4.1)217 (4.8)107 (4.7)110 (4.9)
Receipt of radiation treatment
 No4,298 (42.0)2,265 (49.8)1,179 (51.6)1,086 (48.1)
 Yes5,686 (55.6)2,187 (48.1)1,062 (46.4)1,125 (49.8)
 Unknown238 (2.3)92 (2.0)46 (2.0)46 (2.0)
Receipt of surgery treatment
 Lumpectomy7,033 (68.8)2,882 (63.4)1,445 (63.2)1,437 (63.7)
 Mastectomy3,189 (31.2)1,662 (36.6)842 (36.8)820 (36.3)
Receipt of chemotherapy
 No7,967 (77.9)3,545 (78.0)1,830 (80.0)1,715 (76.0)
 Yes2,255 (22.1)999 (22.0)457 (20.0)542 (24.0)
Ever use of hormone treatment since diagnosis (only among ER+ cases)
 No1,276 (15.2)543 (14.7)299 (15.95)244 (13.34)
 Yes7,140 (84.8)3,161 (85.3)1,576 (84.05)1,585 (86.66)
  • aWomen with two diabetes diagnosis codes [International Statistical Classification of Disease (ICD)-9 code, 250.x] within 180 days of their initial cancer diagnosis were identified as having baseline diabetes. Use of metformin was defined as ever use of the medication study's follow-up period.