Table 1 Characteristics of RCTs about the efficacy of fish oil in patients with type 2 diabetes

Morgan [16]

USA

20

54.3 ± 7.5

Fish oil

20

54.9 ± 6.5

Corn oil

12 weeks

2–4

Sirtori [17]

Italy

203

NA

Fish oil

211

NA

Olive oil

12 months

2

Patti [18]

Italy

8

56.0 ± 8.5

Fish oil

8

57.0 ± 5.7

Olive oil

6 months

2–4

Woodman [19]

Australia

17/18

61.2 ± 9.6/60.9 ± 8.2

EPA/DHA

16

61.5 ± 7.6

Olive oil

6 weeks

2–4

Pedersen [20]

Denmark

23

NA

Fish oil

21

NA

Corn oil

8 weeks

2–4

Mita [21]

Japan

30

59.0 ± 11.2

EPA

30

61.2 ± 8.4

Placebo

2.1 years

2–4

Satoh [22]

Japan

22

51.6 ± 13.1

EPA

22

51.6 ± 15.0

Placebo

3 months

2–4

Kabir [23]

France

12

55.0 ± 6.9

Fish oil

14

55.0 ± 3.7

Paraffin oil

2 months

2–7

Shidfar [24]

Iran

25

53.4 ± 11.7

Fish oil

25

54.1 ± 11.1

Placebo

10 weeks

2–4

Wong [25]

China

49

61.2 ± 9.0

Fish oil

48

59.0 ± 9.3

Olive oil

12 weeks

3,4

Moghadam [26]

Iran

42

55.4 ± 9.9

Fish oil

42

53.0 ± 10.7

Sunflower oil

8 weeks

5

Crochemore [27]

Brazil

14

60.6 ± 7.4

Fish oil

13

61.8 ± 9.1

Placebo

1 month

1–4

Ogawa [28]

Japan

13

79.5 ± 8.6

Fish oil

13

81.2 ± 7.6

Placebo

3 months

2–5,7

Sarbolouki [29]

Iran

32

45.0 ± 4.9

EPA

35

45.3 ± 3.9

Corn oil

12 weeks

1,2

Toupchian [30]

Iran

35

55.8 ± 7.6

Fish oil

33

56.0 ± 7.0

Paraffin oil

8 weeks

1,3,4

Zheng [31]

China

63

59.7 ± 8.8

Fish oil

122

59.4 ± 10.5

Flaxseed and Corn oil

6 months

1–4

Mazaherioun [32]

Iran

44

51.2 ± 7.5

Fish oil

41

50.6 ± 7.2

Paraffin oil

10 weeks

3,4

Mazaherioun [33]

1,2,7

Jacobo-Cejudo [34]

Mexico

29

NA

Fish oil

25

NA

Placebo

24 weeks

1–4,6,7

Wang [35]

China

49

64.6 ± 5.5

Fish oil

50

66.3 ± 5.1

Corn oil

6 months

2–4

Fayh [36]

Brazil

15

50.5 ± 6.1

Fish oil

15

50.7 ± 6.7

Placebo

8 weeks

2–4

Raygan [37]

Iran

30

64.1 ± 9.3

Fish oil

30/30

64.6 ± 9.1/62.0 ± 13.0

Flaxseed oil/Paraffin oil

12 weeks

1,3,4

Rampally [38]

India

14

NA

Fish oil

14

NA

Placebo

3 months

2

Thota [39]

Australia

17

58.0 ± 2.5

Fish oil

16

50.0 ± 2.5

Corn oil

12 weeks

2

Golzari [40]

Iran

18

44.4 ± 3.8

EPA

18

44.7 ± 4.7

Placebo

8 weeks

2–4

Hua [41]

China

51

45.6 ± 5.9

Fish oil

54

43.7 ± 8.6

Corn oil

3 months

1–4,7

Naeini [42]

Iran

25

54.7 ± 7.6

Fish oil

25

56.3 ± 7.8

Paraffin oil

8 weeks

3,4

Golpour [43]

Iran

31

51.2 ± 7.5

Fish oil

30

50.6 ± 7.2

Placebo

10 weeks

1,2

Liu [44]

China

52

62.3 ± 7.6

Fish oil

50

63.8 ± 9.7

Perilla oil

6 months

2–4

Kuang [45]

China

44

59.8 ± 9.9

Fish oil

45

62.2 ± 9.4

Corn oil

2 months

3,4