Increased colorectal cancer risk in prediabetes: A meta-analysis

Table 1 Characteristics of the included cohort studies

Ref.	Country	Design	Population	Sample size	Mean age (years)	Male sex (%)	Definition of PreD	No. of participants with PreD	Mean follow-up duration (years)	Type of cancer	Methods for validation of patients with CRC	Variables adjusted
Jee et al[18], 2005	Korea	PC	General population	1298385	46.9	63.9	IFG	80598	10	Overall CRC	National cancer registry	Age and sex
Rapp et al[19], 2006	Austria	PC	General population	140813	43	45.2	IFG	6828	8.4	Overall CRC	Local cancer registry	Age, sex, smoking, occupation, and BMI
Joshu et al[20], 2012	United States	PC	General population	12792	56.9	45.3	HbA1c (5.7%-6.5%)	2861	13.2	Overall CRC	State cancer registry	Age, sex, ethnicity, study site, education, smoking, BMI, and WC
Parekh et al[21], 2013	United States	PC	General population	4615	37.5	50	IFG	700	35	Colon cancer	Pathological reports	Age, sex, alcohol, smoking, and BMI
Shin et al[22], 2014	Korea	PC	General population	175677	41.8	58.9	IFG	29461	4.7	Overall CRC	National cancer registry	Age, sex, BMI, smoking, alcohol consumption, and regular exercise
Peila et al[23], 2020	United Kingdom	PC	General population	476517	57.8	46	HbA1c (5.7%-6.5%)	64167	7.1	Colon and rectal cancer	ICD codes	Age, sex, ethnicity, education, smoking, physical activity, and HRT
Ke et al[25], 2021	China	PC	General population	9224	52.3	34.3	IGT	1454	7.5	Overall CRC	Local cancer registry	Age and sex
Itoh et al[24], 2021	Japan	RC	General population	1441311	46	56.6	IFG	74836	3.1	Overall CRC	ICD codes	Age, sex, obesity, high WC, hypertension, dyslipidemia, cigarette smoking, alcohol consumption, and physical inactivity
Campbell et al[26], 2022	United States	PC	General population	5049	NR	51.5	HbA1c (5.7%-6.5%)	916	9.5	Overall CRC	Local cancer registry	Age, sex, BMI, smoking, physical activity, alcohol, and HRT
Ahn et al[27], 2024	Korea	RC	General population	1430054	49.8	71.4	IFG	120906	6.4	Overall CRC	National cancer registry	Age, sex, BMI, smoking status, alcohol consumption, physical activity, hypertension, and dyslipidemia
Wang et al[28], 2024	China	PC	General population	1915	59.3	49.9	HbA1c (5.7%-6.5%)	1190	12.9	Overall CRC	Local cancer registry	Age, sex, WC, smoking, alcohol drinking, household annual income, education, physical activity, and intake of vegetables and red meat

PreD: Prediabetes; CRC: Colorectal cancer; PC: Prospective cohort; RC: Retrospective cohort; IFG: Impaired fasting glucose; IGT: Impaired glucose tolerance; HbA1c: Hemoglobin A1c; BMI: Body mass index; WC: Waist circumference; HRT: Hormone replacement therapy; ICD: International Classification of Diseases.

Table 2 Study quality evaluation via the Newcastle-Ottawa scale

Ref.	Representativeness of the exposed cohort	Selection of the non-exposed cohort	Ascertainment of exposure	Outcome not present at baseline	Control for age and sex	Control for other confounding factors	Assessment of outcome	Sufficient long follow-up duration	Adequacy of the follow-up of cohorts	Total
Jee et al[18], 2005	1	1	1	1	1	0	0	1	1	7
Rapp et al[19], 2006	1	1	1	1	1	1	0	1	1	8
Joshu et al[20], 2012	1	1	1	1	1	1	0	1	1	8
Parekh et al[21], 2013	1	1	1	1	1	1	1	1	1	9
Shin et al[22], 2014	1	1	1	1	1	1	0	0	1	7
Peila et al[23], 2020	1	1	1	1	1	1	0	1	1	8
Ke et al[25], 2021	1	1	1	1	1	0	0	1	1	7
Itoh et al[24], 2021	0	1	1	1	1	1	0	0	1	6
Campbell et al[26], 2022	1	1	1	1	1	1	0	1	1	8
Ahn et al[27], 2024	0	1	1	1	1	1	0	1	1	7
Wang et al[28], 2024	1	1	1	1	1	1	0	1	1	8