Table 1. Characteristic of experimental trials included in the meta-analysis.

Trial	Country	Vitamin E group intervention	Control group	Duration weeks(n)	Study Size(n)		Mean age (year)		Male(%)		Diabetes duration(years)		Trial design	Baseline HbA1c(%)	Baseline FPG(mmol/l)	Baseline Vit E (mmol/l)
					T	C	T	C	T	C	T	C
Paolisso 1993	Italy	d-α-tocopherol 900 mg/d	Placebo	12	25	25	71.3	71.3	—	—	8.4	8.4	C1	7.0	8.2	16.3
Reaven 1995	USA	dl-α-tocopherol 1600 IU/d	Placebo	10	10	11	60.8	61.8	100	100	8.6	8.3	P	7.7	9.9	35
Tutuncu 1998	Turkey	dl-α-tocopherol acetate 900 mg/d	Placebo	24	11	10	51.2	59.3	18.2	10	8.8	8.9	P	7.5	7.2	—
Gazis 1999	UK	α-tocopherol 1600 IU/d	Placebo	8	23	25	56.4	57.9	65.2	84	4.3	4.8	P	6.9	9.6	27.8
Paolisso 2000	Italy	Vitamin E 600 mg	Placebo	8	20	20	58.3	56.7	45	60	7.8	7.8	P	7.7	8.3	16.9
Manzella 2001	Italy	All-rac-α-tocopherolAcetate 600 mg/d	Sodium citrate	16	25	25	64.3	65.1	—	—	—	—	P	8.2	9.1	7.1
Park 2002	Korea	α-tocopherol 200 mg/d	Digestive pill	8	48	50	49.4	49.5	56.3	62.8	7.9	8.3	P	10.9	10.4	25.5
Chen 2004	China	Vitamin E 200 mg	Placebo	52	41	41	52	52.4	51.2	48.8	<1	<1	P	7.6	—	—
Economides 2005	USA	All-rac-α-tocopherol Acetate 1800 IU/d	Soybeanoil	24	25	20	59	59	56.7	56.7	9	9	P	7.2	—	28.9
Ble-Castillo 2005	Mexico	α-tocopherol 800 IU/d	Corn strach	6	13	21	51.3	55.3	0	0	<14	<14	P	10.9	12.8	—
Baliarsingh 2005	India	Tocotrienols 6 mg/kg	Rice brain oil	8	10	9	48.5	52.6	50	55.6	5.3	4.3	C1	7.6	6.3	—
Boshtam 2005	Iran	Vitamin E 200 IU/d	Placebo	27	50	50	52.8	54.5	—	—	5.7	13.3	P	9.9	10.8	10.5
Ward 2007	Australia	RRR-α-tocopherol or mixd tocopherols 500 mg/d	Soy bean oil	6	37	18	61	62	67.5	88.9	—	—	P	—	7.3	—
de Oliveira 2011	Brazil	α-tocopherol 800 IU/d	Placebo	16	25	26	62	63	72	57.7	—	—	P	—	7.2	4.7

FPG: fasting plasma glucose; vitE: vitamin E; mixed tocopherols: 60%γ-,25% δ- and 15% α-tocopherol; HbA1c: glycated hemoglobin; USA: United States of America; UK: The United Kingdom; T:treatment group; C: control group; C1: crossover design; P: Parallel design.