The association of serum C-peptide with the risk of cardiovascular events: a meta-analysis and systematic review

Table 2 Summary relative risk (RR) estimates [95% confidence intervals (CIs)] for sub-group analysis of the association between the serum c-peptide levels with the risk of cardiovascular diseases events

Subgroups	Study numbers	Summary RR (95% CI)	Between studies		Between subgroups
Subgroups	Study numbers	Summary RR (95% CI)	I²	P_{heterogeneity}	Q	P_{heterogeneity}
Cohort and case-control studies Region					2.45	0.117
Europe	6	0.99 (0.95–1.03)	34.4	0.178
Other	3	1.12 (0.96–1.30)	8.1	0.334
Diabetes status					0.16	0.688
Diabetic population	7	0.99 (0.96–1.03)	48.3	0.078
General population	2	1.03 (0.85–1.25)	0.0	0.480
Cross-sectional studies
Region					7.99	0.018
Asia	3	1.18 (1.07–1.30)	91.3	< 0.001
America	2	1.61 (1.29–2.00)	81.7	0.019
Europe	2	1.47 (1.16–1.87)	0.0	0.830
Diabetes status					5.18	0.023
Diabetic population	5	1.22 (1.11–1.33)	84.5	< 0.001
General population	2	1.61 (1.29–2.00)	81.7	0.019

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