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Table 1 Descriptive characteristics of the study population

From: Long-term exposure to insulin and volumetric mammographic density: observational and genetic associations in the Karma study

Characteristic

Matched cohort analysis insulin-treated diabetes

Insulin genetic score analysis

Insulin-treated T1D (n = 122)

Non-diabetics (n = 610)

P value

Insulin-treated T2D (n = 237)

Nondiabetics (n = 1161)

P value

Nondiabetics (n = 9437)

Age, years, mean (SD)

49.6 (8.6)

49.6 (8.5)

1.00

62.5 (8.0)

62.3 (7.9)

0.82

57.3 (9.8)

BMI, kg/m2, mean (SD)

25.7 (4.3)

25.1 (4.3)

0.17

29.5 (5.7)

25.3 (3.9)

<  0.001

25.3 (4.1)

Education level, % (n)

  

0.09

  

0.09

 

 Compulsory

8.5 (10)

8.3 (49)

 

27.9 (62)

22.7 (250)

 

16.9 (1376)

 Gymnasium

40.2 (47)

30.2 (178)

 

29.7 (66)

27.2 (300)

 

31.2 (2544)

 University

51.3 (60)

61.5 (362)

 

42.3 (94)

50.1 (552)

 

51.9 (4234)

 Missing

4.1 (5)

3.4 (21)

 

6.3 (15)

5.1 (59)

 

13.6 (1283)

Age at menarche, years, mean (SD)

13.4 (2.0)

13.0 (1.4)

0.02

12.8 (1.5)

13.3 (1.5)

<  0.001

13.2 (1.5)

Parity, % (n)

  

<  0.001

  

0.12

 

 0

22.1 (27)

14.0 (85)

 

17.9 (42)

12.6 (144)

 

12.1 (1129)

 1

25.4 (31)

14.0 (85)

 

14.5 (34)

12.9 (147)

 

14.5 (1354)

 2

36.9 (45)

51.8 (314)

 

42.7 (100)

46.8 (534)

 

47.6 (4460)

  ≥ 3

15.6 (19)

20.1 (122)

 

24.8 (58)

27.8 (317)

 

25.9 (2423)

 Missing

0.0 (0)

0.7 (4)

 

1.3 (3)

1.6 (19)

 

0.8 (71)

Age at first birth, years, mean (SD)

27.3 (5.6)

28.5 (5.3)

0.05

24.3 (4.4)

25.8 (5.0)

<  0.001

26.6 (5.0)

 Missing

5.3 (5)

5.6 (29)

 

6.3 (12)

5.1 (51)

  

Menopausal status, % (n)

  

0.97

  

0.86

 

 Premenopausal

65.6 (80)

65.4 (399)

 

13.5 (32)

14.0 (162)

 

34.1(3216)

 Postmenopausal

34.4 (42)

34.6 (211)

 

86.5 (205)

86.0 (999)

 

65.9 (6221)

OC use (ever), % (n)

73.8 (90)

85.6 (519)

0.001

66.1 (154)

75.3 (853)

0.004

79.0 (6779)

 Missing

0.0 (0)

0.7 (4)

 

1.7 (4)

2.4 (28)

 

9.1 (857)

HRT, % (n)

  

0.23

  

0.52

 

 Never

86.8 (99)

86.9 (504)

 

71.2 (151)

70.6 (730)

 

73.6 (6400)

 Former

7.9 (9)

10.5 (61)

 

25.5 (54)

24.3 (251)

 

21.9 (1909)

 Current

5.3 (6)

2.6 (15)

 

3.3 (7)

5.1 (53)

 

4.8 (423)

 Missing

6.6 (8)

4.9 (30)

 

10.5 (25)

10.9 (127)

 

7.5 (705)

Alcohol intake, % (n)

  

0.02

  

<  0.001

 

 None

27.9 (34)

17.0 (104)

 

44.4 (103)

17.7 (200)

 

18.9 (1602)

 1–25 g/wk

17.2 (21)

26.2 (160)

 

18.5 (43)

23.2 (262)

 

19.3 (1643)

 25–50 g/wk

32.8 (40)

27.7 (169)

 

16.4 (38)

29.5 (333)

 

32.3 (2742)

  > 50 g/wk

21.3 (26)

27.9 (170)

 

20.7 (48)

29.5 (332)

 

28.5 (2508)

 Missing

0.8 (1)

1.1 (7)

 

2.1 (5)

2.9 (34)

 

10.0 (942)

Physical activity, % (n)

  

0.07

  

<  0.001

 

  < 40 MET h/d

40.2 (47)

31.6 (188)

 

54.1 (120)

39.9 (443)

 

35.4 (2913)

 40–45 MET h/d

32.5 (38)

36.8 (219)

 

32.0 (71)

35.4 (393)

 

36.0 (2969)

 45–50 MET h/d

12.8 (15)

20.8 (124)

 

8.6 (19)

16.5 (183)

 

18.6 (1535)

  > 50 MET h/d

14.5 (17)

10.8 (64)

 

5.4 (12)

8.1 (90)

 

10.0 (822)

 Missing

4.1 (5)

2.5 (15)

 

6.3 (15)

4.5 (52)

 

12.7 (1198)

Smoking status, % (n)

  

0.38

  

0.17

 

 Never

52.5 (64)

53.9 (327)

 

41.1 (97)

46.5 (536)

 

46.4 (3977)

 Former

32.0 (39)

34.9 (212)

 

44.5 (105)

42.6 (491)

 

41.7 (3568)

 Current

15.6 (19)

11.2 (68)

 

14.4 (34)

10.9 (125)

 

11.9 (1020)

 Missing

0.0 (0)

0.5 (3)

 

0.4 (1)

0.8 (9)

 

9.2 (872)

Statin therapy (current), % (n)

36.1 (44)

4.3 (26)

<  0.001

61.2 (145)

11.5 (134)

<  0.001

8.9 (839)

Low-dose aspirin (current), % (n)

15.6 (19)

2.1 (13)

<  0.001

35.0 (83)

6.5 (76)

<  0.001

5.1 (483)

Charlson comorbidity index, % (n)

  

<  0.001

  

<  0.001

 

 0

82.0 (100)

97.0 (592)

 

73.8 (175)

92.2 (1070)

 

94.5 (8913)

 1

14.8 (18)

2.6 (16)

 

15.2 (36)

6.5 (75)

 

4.8 (452)

  ≥ 2

3.3 (4)

0.3 (2)

 

11.0 (26)

1.4 (16)

 

0.8 (72)

Benign breast disease, % (n)

  

0.77

  

0.78

 

  No

78.1 (89)

76.8 (464)

 

75.8 (175)

74.9 (856)

 

76.8 (7084)

 Yes

21.9 (25)

23.2 (140)

 

24.2 (56)

25.1 (287)

 

23.2 (2145)

 Missing

6.6 (8)

1.0 (6)

 

2.5 (6)

1.6 (18)

 

2.2 (208)

Family history of breast cancer, % (n)

  

0.05

  

0.04

 

 No

84.0 (100)

90.2 (534)

 

80.9 (182)

86.1 (963)

 

87.0 (7944)

 Yes

16.0 (19)

9.8 (58)

 

19.1 (43)

13.9 (155)

 

13.0 (1188)

 Missing

2.5 (3)

3.0 (18)

 

5.1 (12)

3.7 (43)

 

3.2 (305)

Age at diagnosis, years, mean (SD)

19.9 (7.6)

–

 

54.8 (8.2)

–

 

–

Diabetes duration, years, mean (SD)

29.7 (10.2)

–

 

4.9 (2.5)

–

 

–

Insulin therapy, % (n)

       

 Glargine insulin

53.3 (65)

–

 

31.2 (74)

–

 

–

 Nonglargine insulin

46.7 (57)

–

 

68.8 (163)

–

 

–

Comedication metformin, % (n)

       

 No

95.9 (117)

–

 

47.3 (112)

–

 

–

 Yes

4.1 (5)

–

 

52.7 (125)

–

 

–

  1. Abbreviations: T1D Type 1 diabetes, T2D Type 2 diabetes, BMI Body mass index, OC Oral contraceptive, HRT Hormone replacement therapy, MET Metabolic equivalent of activity level
  2. Study populations: matched cohort analysis including insulin-treated diabetes and insulin genetic score analysis including women with available genotyping data and no known diabetes. All women in the study population were free of cancer at study entry (i.e., the baseline screening visit). In total, 21 T2D patients could not be matched to a maximum of 5 individuals (i.e., 20 patients were matched to 4 individuals, and 1 patient was matched to 1 individual), leaving 610 and 1161 age-matched women without diabetes for insulin-treated T1D and T2D analyses, respectively. Participant characteristics were compared using t tests for continuous data and chi-squared tests for categorical variables
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Breast Cancer Research

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