Table 3 Characteristics of the study subjects according to changes in SMI over one year (N = 11,639)

SMI 1-year increases (%)

− 0.80 (0.66)

0.43 (0.28)

1.65 (0.80)

Age (year)

51.1 (7.9)

52.2 (7.9)

50.5 (7.8)

51.6 (7.8)

49.7 (8.0)

50.8 (8.0)

< 0.001

< 0.001

0.001

Sex (women)

2444 (37.5)

–

1724 (46.2)

–

725 (52.5)

–

< 0.001

–

–

Waist circumference (cm)

81.4 (8.2)

82.2 (8.2)

80.9 (8.6)

80.9 (8.3)

80.2 (8.6)

79.0 (8.1)

< 0.001

< 0.001

< 0.001

Body weight (kg)

64.5 (10.1)

65.2 (10.1)

63.8 (10.5)

63.4 (10.4)

63.1 (10.5)

61.4 (10.0)

< 0.001

< 0.001

< 0.001

BMI (kg/m²)

23.3 (2.5)

23.6 (2.5)

23.3 (2.6)

23.1 (2.6)

23.2 (2.7)

22.5 (2.5)

0.750

< 0.001

< 0.001

Obesity, n (%)

1527 (23.4)

1817 (27.9)

898 (24.1)

800 (21.4)

347 (25.1)

220 (15.9)

0.355

< 0.001

< 0.001

ASM (kg)

20.5 (4.2)

20.2 (4.2)

19.7 (4.3)

19.9 (4.3)

19.2 (4.3)

19.7 (4.3)

< 0.001

< 0.001

< 0.001

Fat mass (kg)

15.4 (4.4)

16.7 (4.4)

16.4 (4.5)

15.8 (4.3)

16.7 (4.5)

14.3 (4.1)

< 0.001

< 0.001

< 0.001

Percent fat mass (%)

24.0 (6.0)

25.7 (5.9)

25.7 (6.0)

25.0 (5.9)

26.6 (6.1)

23.4 (5.9)

< 0.001

< 0.001

< 0.001

SMI (%)

31.7 (3.1)

30.9 (3.1)

30.7 (3.1)

31.2 (3.1)

30.3 (3.2)

31.9 (3.2)

< 0.001

< 0.001

< 0.001

ASM/BMI (m²)

0.881 (0.155)

0.857 (0.151)

0.846 (0.153)

0.859 (0.154)

0.826 (0.156)

0.875 (0.160)

< 0.001

< 0.001

< 0.001

Hypertension, n (%)

627 (9.6)

715 (11.0)

333 (8.9)

356 (9.5)

119 (8.6)

130 (9.4)

0.345

0.037

0.035

SBP (mmHg)

113.7 (14.9)

117.8 (15.3)

114.4 (15.1)

116.0 (15.5)

114.7 (15.5)

114.4 (15.9)

0.017

< 0.001

< 0.001

DBP (mmHg)

70.3 (10.3)

74.6 (10.8)

71.0 (10.7)

73.0 (11.1)

71.0 (11.1)

71.6 (11.4)

0.001

< 0.001

< 0.001

Smoking, never/past/current, n (%)

3402/1944/1179 (52.1/29.8/18.1)

–

2209/994/531 (59.2/26.6/14.2)

–

869/319/192 (63.0/23.1/13.9)

–

< 0.001

–

–

Regular exercise, n (%)

829 (12.7)

–

573 (15.4)

–

236 (17.1)

–

< 0.001

–

–

Family history of diabetes, n (%)

590 (9.0)

–

417 (11.2)

–

156 (11.3)

–

0.001

–

–

IFG, n (%)

681 (10.4)

872 (13.4)

418 (11.2)

451 (12.1)

172 (12.5)

150 (10.9)

0.073

0.018

< 0.001

Diabetes, n (%)

–

91 (1.4)

–

32 (0.9)

–

7 (0.5)

–

0.003

–

HbA_1c (%)

5.3 (0.4)

5.4 (0.4)

5.3 (0.4)

5.4 (0.4)|

5.3 (0.5)

5.4 (0.4)

0.098

0.070

< 0.001

Fasting glucose (mg/dL)

89.0 (8.7)

91.2 (9.6)

89.2 (8.7)

90.3 (9.1)

89.4 (9.4)

89.5 (8.9)

0.168

< 0.001

< 0.001

Fasting insulin^a (μIU/mL)

8.51 (3.38)

8.29 (3.56)

8.62 (3.41)

7.83 (3.54)

8.47 (3.60)

7.29 (3.58)

0.379

< 0.001

< 0.001

HOMA-IR^a

1.89 (0.80)

1.89 (0.89)

1.92 (0.80)

1.76 (0.86)

1.90 (0.86)

1.63 (0.88)

0.249

< 0.001

< 0.001

eGFR (mL/min/1.73m²)

88.5 (12.1)

88.1 (12.6)

88.8 (12.3)

88.4 (13.1)

89.5 (13.4)

88.7 (14.2)

0.042

0.299

0.496

Total cholesterol (mg/dL)

195.0 (31.9)

199.1 (32.8)

196.9 (33.2)

197.1 (32.2)

196.0 (33.7)

193.9 (32.5)

0.018

< 0.001

< 0.001

Triglycerides (mg/dL)

110.8 (60.2)

115.0 (58.8)

114.1 (69.9)

107.9 (56.1)

109.9 (55.6)

97.8 (45.3)

0.028

< 0.001

< 0.001

HDL cholesterol (mg/dL)

58.3 (13.6)

56.4 (13.5)

58.8 (14.0)

57.5 (13.8)

59.4 (14.3)

59.3 (13.9)

0.016

< 0.001

< 0.001

LDL cholesterol (mg/dL)

123.2 (28.0)

124.2 (27.8)

124.6 (29.1)

121.2 (28.2)

123.9 (29.4)

116.5 (28.0)

0.043

< 0.001

< 0.001

C-reactive protein (mg/L)

0.11 (0.36)

0.11 (0.32)

0.11 (0.27)

0.10 (0.24)

0.10 (0.19)

0.09 (0.24)

0.144

0.069

0.125