Table 1 Characteristics of included studies

Ahn et al. (2016) [27]

Korea

127

Bladder

Yes

HbA_1c ≥ 7% vs. <  7%

50 months

Cancer recurrence-free survival; progression-free survival

RFS was defined as the time from initial TUR to first tumor recurrence (regardless of grade or stage),PFS was define as the time from initial TUR to tumor progression, any increase in grade (G1/2 to G3) or stage (Ta to T1 or T2, T1 to T2) after repeat TUR for recurrence.

Boursi et al. (2016) [28]

UK

7916

Bladder, breast, colorectal, pancreatic, prostate

Yes

Continuous HbA_1c

4.1 years (bladder);

4.4 (breast);

3.3 (colorectal);

1.2 (pancreatic);

4.2 (prostate)

Overall survival

All-cause death

Cheon et al. (2014) [29]

Korea

65

Pancreatic

Yes

HbA_1c ≥ 7% vs. <  7%

9 months

Overall survival

All-cause death

Huang et al. (2020) [30]

Taiwan, China

33

Bladder

Yes

HbA_1c ≥ 7% vs. <  7%

45 months

Cancer recurrence-free survival

RFS was defined as the period from the date of the initial TUR of bladder tumour to the date of the operation in which the first cancer recurrence was found.

Hwang et al. (2011) [31]

Korea

92

Bladder

No

HbA_1c ≥ 7% vs. <  7%

30 months

Cancer recurrence; cancer progression

RFS was defined as the time from initial TUR to first tumour recurrence (regardless of grade or stage), whereas PFS was defined as the time from initial TUR to tumour progression (any increase in grade [G1/2 to G3] or stage [Ta to T1 or T2, T1 to T2]) after repeat TUR for recurrence.

Kaneda et al. (2012) [32]

Japan

26

HCC

Yes

HbA_1c ≥ 6.5% vs. <  6.5%

23 months

Cancer recurrence

NR

Kang et al. (2016) [33]

Korea

135

Bladder

Yes

HbA_1c ≥ 7% vs. <  7%

33.8 months

Cancer recurrence-free survival; Bladder cancer specific survival; overall survival

RFS, CSS, and OS, were defined from the date of surgery to the date of recurrence, death from upper tract urothelial carcinoma, and death from any cause

Komatsu et al. (2020) [34]

Japan

259

Lung

No

Continuous HbA_1c; HbA_1c ≥ 7% vs. <  7%

39 months

Overall survival

All-cause death

Lee et al. (2016) [35]

Korea

77

Pancreatic

Yes

HbA_1c ≥ 9% vs. <  9%

20 months

Overall survival; disease-free survival

Disease-free survival: cancer recurrence or death

Lee et al. (2017) [36]

Korea

61

Colon

Yes

HbA_1c ≥ 8% vs. <  8%

NR

Overall survival

All-cause death

Li et al. (2017) [37]

China

89

Cervical

Yes

continuous HbA_1c; HbA_1c ≥ 7% vs. <  7%

39 months

Cancer recurrence-free survival; cancer specific mortality; overall survival

RFS, CSS and OS were calculated from the date of neoadjuvant chemotherapy until the date of events (recurrence or death from cervical cancer or death from any cause)

Nik-Ahd et al. (2019) [38]

USA

1409

Prostate

Yes

Continuous HbA_1c;

6.8 years

Cancer metastases; cancer recurrence; overall survival; prostate-specific cancer mortality

Metastases were defined as the first metastasis determined from any type of imaging test.

Okamura et al. (2017) [39]

Japan

64

Oesophageal

Yes

HbA_1c ≥ 7% vs. <  7%

NR

Overall survival; disease-specific mortality

OS and disease-specific survivals were calculated from either surgery to death or last follow-up

Siddiqui et al. (2008) [40]

USA

155

Colorectal

Yes

HbA_1c ≥ 7.5% vs. <  7.5%

NR

overall survival; cancer-specific mortality

All-cause death; cause-specific death

Tai et al. (2015) [41]

Taiwan, China

55

Bladder

Yes

HbA_1c ≥ 7% vs. <  7%

51 months

Cancer recurrence-free survival

Cancer recurrence referred to tumour relapse in operative filed, regional lymph nodes and/or distant metastasis.