Pre-existing diabetes mellitus increases the risk of gastric cancer: A meta-analysis

Table 2 Preexisting diabetes and risk of gastric cancer by subgroup meta-analysis using random effect model

	Studies (n)	RR (95%CI)	I2% (95%CI)
Overall	27	1.19 (1.08-1.31)	70.7 (56.8-80.2)
Countries
East Asian countries1	10	1.19 (1.02-1.38)	60.1 (20.0-80.1)
Western countries2	17	1.18 (1.03-1.36)	75.6 (61.0-84.8)
Study type
Cohort study	18	1.20 (1.08-1.34)	75.5 (61.2-84.5)
Case control study	9	1.12 (0.87-1.45)	57.9 (11.8-79.9)
Sex
Male	12	1.10 (0.97-1.24)	74.9 (55.7-85.8)
Female	9	1.24 (1.01-1.52)	58.9 (14.1-80.3)
DM criteria
Registration	8	1.21 (1.02-1.44)	83.0 (67.8-91.0)
Measured3	5	1.15 (1.01-1.32)	35.5 (0.0-75.8)
Self report	14	1.13 (0.93-1.39)	65.2 (38.6-80.3)
Interval4
One and more years	15	1.15 (1.02-1.31)	67.5 (44.3-81.0)
Quality (NOS)
High quality (8 and more)	17	1.17 (1.05-1.31)	73.4 (57.0-83.6)
Low quality (7 and less)	10	1.20 (0.97-1.49)	61.2 (22.6-80.5)
Adjustment for risk factor
Smoking5	12	1.17 (1.01-1.34)	52.6 (8.7-75.4)
H. pylori5	2	2.35 (1.24-4.46)	0.0 (UC)
Cancer site
Cardia cancer	2	1.39 (0.72-2.69)	82.3 (UC)
Noncardia cancer	2	1.19 (0.80-1.77)	59.6 (UC)

¹Japan, South Korea;

²United States, Canada, Europe and Israel;

³Using fasting blood glucose or HbA1c as criteria;

⁴The least cancer-free time of subject according to study design;

⁵The subgroup of studies designed to include the risk factor as adjustment variables. RR: Relative risk; UC: Unable to calculate due to low degree of freedom; NOS: Newcastle-Ottawa Quality Assessment Scale; H. pylori: Helicobacter pylori.