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. 2026 Jan 27;23:27. doi: 10.1186/s12986-025-01061-5

Table 2.

Results of subgroup analysis of included randomizes controlled trials in meta-analysis of melatonin supplementation on glycemic indices

Variable FBS (mg/dl) Insulin (µIU/ml) HbA1c (%) HOMA-IR QUICKI

Dose < 8 mg

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

15

−2.83(−5.73, 0.08)

0.057

60.8

0.001

8

1.12(−0.93, 3.18)

0.283

38.4

0.123

5

−0.44(−1.05, 0.17)

0.154

96.6

< 0.001

8

−0.14(−0.60, 0.31)

0.541

81.5

< 0.001

Not sufficient data

Dose ≥ 8 mg

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

12

−2.47(−4.92, −0.03)

0.047

41.8

0.06

8

−2.16(−2.27, −1.57)

< 0.001

35.2

0.147

2

−0.49(−0.86, −0.13)

0.009

0.00

0.481

8

−0.75(−1.06, −0.45)

< 0.001

60.5

0.013

6

0.01(0.01, 0.01)

< 0.001

86.7

< 0.001

Duration ≤ 10w

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

13

−3.12(−6.18, −0.06)

0.046

65.0

< 0.001

6

0.89(−4.62, 6.40)

0.753

79.6

< 0.001

4

−0.72(−1.31, −0.13)

0.017

86.9

< 0.001

6

−0.70(−1.81, 0.42)

0.220

83.5

< 0.001

Not sufficient data

Duration > 10w

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

14

−2.27(−4.62, 0.08)

0.058

32.2

0.094

10

−1.73(−2.27, −1.20)

< 0.001

31.5

0.157

3

−0.08(−0.40, 0.24)

0.631

73.1

0.024

10

−0.46(−0.80, −0.11)

0.009

86.7

< 0.001

7

0.01(0.00, 0.01)

< 0.001

93.7

< 0.001

BMI (Kg/m 2 ) ≤ 27

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

8

−3.07(−5.15, −0.99)

0.004

21.9

0.0255

5

−1.79(−2.95, −0.63)

0.002

39.8

0.156

2

−0.25(−0.83, 0.33)

0.393

83.6

0.013

7

−0.29(−0.69, 0.11)

0.159

88.2

< 0.001

4

0.00(−0.01, 0.01)

0.642

93.3

< 0.001

BMI (Kg/m2 ) >27

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

16

−3.14(−6.58, 0.29)

0.073

65.2

< 0.001

11

−1.53(−2.64, −0.41)

0.007

68.5

< 0.001

3

−0.26(−0.79, 0.26)

0.329

77.00

0.013

9

−0.84(−1.39, −0.29)

0.003

72.00

< 0.001

3

0.01(+ 0.00, 0.02)

0.002

93.0

< 0.001

T2DM

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

8

−9.70(−17.12, −2.29)

0.010

48.3

0.060

4

−1.61(−3.26, 0.04)

0.055

67.2

0.027

5

−0.70(−1.18, −0.22)

0.004

83.8

< 0.001

4

−0.74(−1.46, −0.03)

0.042

69.8

0.019

3

0.01(0.01, 0.02)

< 0.001

88.9

< 0.001

Non-T2DM

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

19

−1.91(−3.70, −0.11)

0.038

51.7

0.005

12

−1.53(−2.53, −0.52)

0.003

62.5

0.002

2

0.02(−0.10, 0.15)

0.719

20.10

0.263

12

−0.44(−0.79, −0.08)

0.016

85.50

< 0.001

4

0.00(−0.01, 0.01)

0.685

93.0

< 0.001

BaselineFBS (mg/dl) < 100

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

12

−1.84 (−4.17, 0.99)

0.121

58.4

0.006

8

−1.83 (−4.02, 0.37)

0.103

67.2

0.003

2

0.02 (−0.10, 0.15)

0.719

20.1

0.263

10

−0.44 (−0.84, −0.05)

0.029

87.5

< 0.001

3

0.0 (−0.01, 0.01)

0.677

95.1

< 0.001

Baseline FBS (mg/dl) ≥ 100

No. of studies

WMD (95%CI)

P-value

I2 (%)

P-heterogeneity

15

−3.96 (−7.11, −0.80)

0.014

44.4

0.033

8

−1.40 (−2.26, −0.54)

0.001

59.00

0.017

5

−0.70(−1.18, −0.22)

0.004

83.8

< 0.001

6

−0.67 (−1.13, −0.21)

0.004

57.7

0.038

4

0.01 (0.00, 0.02)

0.004

90.1

< 0.001