Table 1.

Baseline characteristics of the metabolic sub-study population

	Metformin (n = 237)		Placebo (n = 255)
Age (mean, SD)	52.1 (±12)		52.6 (±)
Race
Asian	4	(1.7%)	6	(2.4%)
Black	2	(0.8%)	3	(1.2%)
Native	3	(1.2%)	3	(1.2%)
White	227	(95.8%)	239	(93.7%)
Unknown	1	(0.4%)	4	(1.6%)
BMI (median, range)	27.37	(17.68, 46.48)	27.27	(18.73, 46.07)
T stage (neoadjuvant)
cT1	3	(9.6%)	1	(3.7%)
cT2	18	(58.1%)	13	(48.1%)
cT3	10	(32.3%)	13	(48.1%)
N stage (neoadjuvant)
cN0	6	(19.4%)	8	(29.6%)
cN1-3	25	(80.6%)	19	(70.4%)
T stage (adjuvant)
T1	74	(36.0%)	87	(38.2%)
T2	114	(55.3%)	124	(54.4%)
T3	18	(8.7%)	17	(7.4%)
N stage (adjuvant)
N0	97	(47.1%)	116	(50.9%)
N1-3	109	(52.9%)	112	(49.1%)
Hormone receptor
ER and/or PgR positive	173	(73.0%)	190	(72.8%)
ER and PgR negative	64	(27.0%)	71	(27.2%)
HER2
Positive	41	(17.3%)	36	(14.1%)
Negative	196	(82.7%)	219	(85.9%)
Histologic Grade
Grade I	24	(10.1%)	24	(9.4%)
Grade II	87	(36.7%)	100	(39.2%)
Grade III	125	(52.7%)	130	(51.0%)
Unknown	1	(0.4%)	1	(0.4%)
Surgery
Mastectomy	117	(49.4%)	106	(41.6%)
Lumpectomy	120	(50.6%)	149	(58.4%)
Chemotherapy
Yes - neoadjuvant	31	(13.1%)	27	(10.6%)
- adjuvant	179	(75.5%)	197	(77.3%)
No	27	(11.4%)	31	(12.1%)
Hormone Therapy
Yes - neoadjuvant	3	(1.3%)	0	(0%)
- adjuvant	151	(63.7%)	173	(67.8%)
No	83	(35.0%)	82	(32.2%)
Adjuvant Trastuzumab
Yes	40	(16.9%)	33	(12.9%)
No	197	(83.1%)	222	(87.1%)

^*Range = Interquartile Range; SD= standard deviation; ER = estrogen receptor; PgR = progesterone receptor.