Table 1 Characteristics of included studies. NA = not available, DM = diabetes mellitus, NOS = The Newcastle–Ottawa scale.

Li¹⁹

China Hainan

Prospective controlled study

3 months

106/84

101/85

65.1 (12.3)

64.6 (12.5)

NA

7

Misra²⁷

New Zealand

Prospective cohort study

6 months

23

28

74.4 (7.4)

71.2 (7.6)

Duration (11.54 years) HbA1c% (DM:nDM 7.5:5.7, P < 0.001)

8

Zhu²⁸

China Beijing

Prospective controlled study

1 month

16/17

15/20

60–80

60–80

Blood glucose < 8.3 mmol/L, diabetic course > 5a

8

Yan²⁹

China Guizhou

Prospective controlled study

3 months

30/32

51/46

69.6 (55–85)

65.6 (52–82)

Diabetic course > 10a, Diabetic course < 10a

8

Su³⁰

China Liaoning

Prospective controlled study

1 month

31

39

50–80

50–80

Blood glucose < 8.3 mmol/L, diabetic course < 15a

8

Liu³¹

China Hebei

Prospective controlled study

1 week

16/14

17/13

64.7 (3.6)

69.6 (5.4)

NA

8

Zhao³²

China Shandong

Prospective controlled study

3 months

24/26

26/24

64.8 (55–83)

63.2 (52–80)

NA

8

Wang³³

China inner Mongolia

Prospective controlled study

6 months

36/24

24/16

69.2 (8.2)

65.3 (11)

NA

7

Yang³⁴

China Guangzhou

Prospective controlled study

3 months

33/32

34/41

68.1 (50–84)

67.8 (51–83)

Blood glucose < 6. 6–10 mmol/L Duration (1–17 years)

8

Hugod³⁵

Denmark

Prospective controlled study

3 months

30

30

75.4 (9.3)

75.6 (8.6)

HbA1c%(7.08 (1.43))

8

Wu³⁶

China Shaanxi

Prospective controlled study

3 months

31

28

50–80

50–80

Diabetic course < 12a

7

Wu³⁷

China Hainan

Prospective controlled study

3 months

33/31

26/24

65.6 (52–82)

66.8 (50–84)

NA

8

Morikubo¹⁷

Japan

Prospective controlled study

1 month

93

93

68.8 (8.9)

68.6 (8.8)

NA

8