Table 1 Baseline characteristics of 250,312 female UK Biobank participants by diabetes status and subtypes.

From: Diabetes mellitus and risk of breast cancer: a large-scale, prospective, population-based study

Characteristic

No diabetes

T1Da

T2D

n = 235,025

n = 575

Prevalent

Incident

n = 7891

n = 6821

Age at assessment (years), mean (SD)

56.0 (8.0)

53.4 (8.1)

59.8 (6.9)

58.6 (7.5)

White, n (%)

222,017 (94.5)

514 (89.4)

6652 (84.3)

5877 (86.2)

TDI, mean (SD)

−1.40 (3.00)

−0.54 (3.30)

−0.27 (3.38)

−0.35 (3.38)

BMI (kg/m2), mean (SD)

26.8 (4.9)

28.0 (5.6)

32.6 (6.6)

32.1 (6.2)

Physical activity (METh/week), median (IQR)

37.0 (48.8)

36.0 (48.0)

35.8 (48.7)

35.5 (51.5)

Smoking status and intensity, n (%)

  Never

140,743 (59.9)

347 (60.3)

4477 (56.7)

3674 (53.9)

  Former

72,557 (30.9)

166 (28.9)

2643 (33.5)

2160 (31.7)

  Current, <15 cig/day

7668 (3.3)

19 (3.3)

207 (2.6)

261 (3.8)

  Current, ≥15 cig/day

7707 (3.3)

22 (3.8)

353 (4.5)

492 (7.2)

  Current, intensity unknown

5134 (2.2)

12 (2.1)

127 (1.6)

165 (2.4)

Alcohol consumption, n (%)

  Never

20,561 (8.7)

79 (13.7)

1805 (22.9)

1294 (19.0)

  Special occasions or 1–3 times per month

63,873 (27.2)

167 (29.0)

3314 (42.0)

2669 (39.1)

  1–4 times per week

110,852 (47.2)

229 (39.8)

2156 (27.3)

2276 (33.4)

  Daily or almost daily

39,140 (16.7)

96 (16.7)

566 (7.2)

542 (7.9)

Education, n (%)

  Higher

87,843 (37.4)

227 (39.5)

2151 (27.3)

1646 (24.1)

  Secondary

95,838 (40.8)

241 (41.9)

2767 (35.1)

2451 (35.9)

  Vocational

10,228 (4.4)

15 (2.6)

429 (5.4)

443 (6.5)

  Other

38,995 (16.6)

83 (14.4)

2458 (31.1)

2159 (31.7)

Family history of BCa, n (%)

15,237 (6.5)

28 (4.9)

384 (4.9)

332 (4.9)

Ever had a mammogram, n (%)

183,289 (78.0)

382 (66.4)

6968 (88.3)

5818 (85.3)

Ever OCs use, n (%)

191,405 (81.4)

412 (71.7)

5568 (70.6)

4980 (73.0)

Ever HRT use, n (%)

86,894 (37.0)

182 (31.7)

3531 (44.7)

3164 (46.4)

Age at menarche (years), mean (SD)

12.6 (2.7)

12.4 (3.5)

12.3 (3.0)

12.4 (3.0)

Menopause, n (%)

169,913 (72.3)

354 (61.6)

6975 (88.4)

5749 (84.3)

Parity, n (%)

  Nulliparous

44,229 (18.8)

179 (31.1)

1337 (16.9)

1049 (15.4)

  1 child

31,333 (13.3)

111 (19.3)

1026 (13.0)

889 (13.0)

  2 children

103,377 (44.0)

182 (31.7)

2986 (37.8)

2627 (38.5)

  3 or more children

55,428 (23.6)

99 (17.2)

2480 (31.4)

2212 (32.4)

Age at first birth (years), mean (SD)b

26.1 (5.2)

26.2 (5.4)

24.3 (4.9)

24.0 (4.8)

Metformin, n (%)

N/A

N/A

4368 (55.4)

124 (1.8)

Insulin, n (%)

N/A

N/A

1428 (18.1)

22 (0.3)

Testosterone (nmol/L), median (IQR)

1.02 (0.65)

1.16 (0.87)

0.98 (0.66)

1.03 (0.71)

SHBG (nmol/L), mean (SD)

63.2 (30.8)

72.9 (39.4)

41.4 (25.4)

42.4 (25.5)

IGF-1 (nmol/L), mean (SD)

21.2 (5.7)

18.2 (5.8)

19.2 (6.5)

19.3 (6.2)

HbA1c (mmol/mol), median (IQR)

34.9 (4.7)

60.1 (17.8)

49.8 (14.8)

41.1 (6.8)

CRP (mg/L), median (IQR)

1.30 (2.16)

1.92 (3.35)

2.49 (4.03)

3.35 (4.82)

  1. BCa breast cancer, BMI body mass index, cig cigarettes, CRP C-reactive protein, HbA1c haemoglobin A1c, HRT hormone replacement therapy, IGF insulin-like growth factor, IQR interquartile range, METh metabolic equivalent of task hours, OC oral contraceptive, SD standard deviation, SHBG sex hormone-binding globulin, T1D type 1 diabetes, T2D type 2 diabetes, TDI Townsend deprivation index.
  2. aAll type 1 diabetes cases were identified prior to baseline assessment.
  3. bMean age at first birth was calculated among parous women.
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