Table 1.

Characteristics of the studies included in the meta-analysis.

Study ID	Year	Country	Study design	Sample size	Male (%)	Follow-up duration	Follow-up rate (%)	HbA1c levels	Study outcomes	NOS score
Sato et al. [21]	2010	Canada	Prospective cohort	130	70.8	30 days	100%	<6.5% versus ≥6.5%	All-cause mortality, myocardial failure, stroke, dialysis, serious infection	4/3/2
Halkos et al. [22]	2008	USA	Prospective cohort	3089	72.6	In-hospital stay	100%	≤7% versus >7%	All-cause mortality, MI, renal failure, atrial fibrillation, cerebrovascular accident	4/2/1
Halkos et al. [23]	2008	USA	Prospective cohort	3201	71.6	2.8 ± 1.4 years	NA	≤7% versus >7%	Cerebrovascular disease, renal insufficiency, CHF, MI, peripheral vascular disease	3/2/1
Knapik et al. [24]	2011	Poland	Prospective cohort	735	66.3	In-hospital stay	100%	≤7% versus >7%	All-cause mortality, stroke, renal failure, wound infection, perioperative MI	4/3/2
Alserius et al. [25]	2008	Sweden	Prospective cohort	122	54.9	3.5 years	100%	≤7% versus >7%	All-cause mortality, superficial sternal wound infections, mediastinitis	4/1/2
Santos et al. [26]	2015	Argentina	Prospective cohort	96	82.3	In-hospital stay	NA	≤7% versus >7%	All-cause mortality, CHF, MI, renal failure, stroke	4/2/2
Faritous et al. [27]	2014	Iran	Prospective cohort	216	63.9	In-hospital stay	NA	≤7% versus >7%	All-cause mortality, arrhythmia, AMI, CHF	4/1/2
Tsuruta et al. [28]	2011	Japan	Prospective cohort	306	79.1	3.6 ± 1.7 years	100%	<6.5% versus ≥6.5%	MI, arrhythmia, congestive heart failure, sudden death	4/3/2

CHF: congestive heart failure; MI: myocardial infarction; NA: not available.