Table 1 Baseline characteristics of the study population

Age (years)

49.4 ± 16.3

57.9 ± 14.1

49.1 ± 16.3

<  0.001

Female (%)

53.6

46.6

53.9

<  0.001

Post-menopausal women (%)

26.6

26.2

36.9

<  0.001

Body mass index (kg/m²)

23.7 ± 3.4

23.4 ± 3.1

23.7 ± 3.4

0. 006

Obesity classification (%)

0.026

 Under weight

4.1

3.4

4.1

 Normal weight

39.1

41.4

39.0

 Over weight

24.0

26.7

23.9

 Obesity

32.8

28.4

33.0

 Alcohol (%)

72.8

68.2

73.0

0.003

Smoking (%)

0.010

 None

57.9

53.0

58.1

 Former smoker

20.5

24.1

20.3

 Current smoker

21.6

22.9

21.6

 Systolic blood pressure (mmHg)

119.6 ± 17.1

123.3 ± 17.5

119.4 ± 17.1

<  0.001

 Diastolic blood pressure (mmHg)

76.2 ± 10.5

76.9 ± 10.3

76.2 ± 10.5

0.066

Blood pressure status (%)

<  0.001

 Prehypertension

25

27.3

24.9

 Hypertension

31.7

41.2

31.3

 Fasting blood glucose (mg/dL)

98.1 ± 21.7

99.7 ± 19.6

98.0 ± 21.8

0.016

Impaired glucose tolerance (%)

<  0.001

 Impaired fasting glucose

19.7

19.6

22.7

 Diabetes mellitus

10.4

10.2

13.4

 Cardiovascular disease (%)

2.6

3.7

2.5

0.063

 Hypercholesterolemia (%)

15.0

17.3

14.9

0.071

 Hemoglobin (g/dL)

14.1 ± 1.6

14.1 ± 1.5

14.1 ± 1.6

0.511

 Anemia (%)

8.0

9.2

7.9

0.229

 Estimated GFR (mL/min/1.73 m²)

94.7 ± 17.2

83.7 ± 17.7

88.6 ± 17.3

<  0.001

 Estimated GFR under 60 mL/min/1.73 m² (%)

3.7

7.3

3.6

<  0.001

 Serum 25(OH)D (ng/mL)^a

16.6 (13.1–20.8)

33.1 (31.4–35.7)

16.3 (12.9–20.2)

<  0.001

 Glycosuria (%)

2.5

2.1

2.5

0.534

 Proteinuria (%)

1.1

0.6

1.1

0.215

 Hematuria (%)

15.5

12.3

15.7

0.011