Table 2.
Summary of subgroup analyses of saffron on FPG, HbA1c, insulin levels, QUICKI, and HOMA-IR in diabetes.
| Subgroup | Studies included | WMD | 95% CI | p of pooling WMD | Heterogeneity | ||
|---|---|---|---|---|---|---|---|
| I2% | p | p between sub-group | |||||
| FPG (mg/dL) | |||||||
| Study design | 0.002 | ||||||
| Single-blinded | 1 | 0.36 | −2.37, −3.09 | 0.796 | – | – | |
| Double-blinded | 7 | −9.57 | −15.53, −3.60 | 0.002 | 43.2 | 0.103 | |
| Triple-blinded | 4 | −12.55 | −24.45, −0.66 | 0.039 | 48.7 | 0.119 | |
| Type of diabetes | 0.595 | ||||||
| T2DM | 8 | −9.05 | −16.64, −1.46 | 0.019 | 71.5 | 0.001 | |
| Others | 4 | −6.86 | −9.61, −4.11 | <0.001 | 0.0 | 0.498 | |
| Type of intervention | 0.070 | ||||||
| Saffron | 7 | −5.98 | −11.62, −0.34 | 0.038 | 77.1 | <0.001 | |
| Crocin | 5 | −15.30 | −23.66, −6.93 | <0.001 | 0.0 | 0.958 | |
| Form of intervention | 0.150 | ||||||
| Tablet | 7 | −9.41 | −16.25, −2.57 | 0.007 | 5.6 | 0.384 | |
| Capsule | 3 | −21.77 | −42.80, −0.74 | 0.043 | 77.7 | 0.011 | |
| Others | 2 | −2.99 | −9.58, 3.60 | 0.374 | 91.1 | 0.001 | |
| Dose of intervention (mg/day) | 0.010 | ||||||
| ≤30 | 9 | −13.19 | −19.99, −6.40 | <0.001 | 47.8 | 0.053 | |
| >30 | 3 | −1.62 | −7.21, 3.97 | 0.571 | 47.6 | 0.148 | |
| Duration of intervention (weeks) | 0.189 | ||||||
| <12 | 4 | −5.56 | −11.44, 0.32 | 0.064 | 83.6 | <0.001 | |
| ≥12 | 8 | −12.39 | −20.73, −4.06 | 0.004 | 35.0 | 0.149 | |
| HbA1c (%) | |||||||
| Study design | 0.001 | ||||||
| Single-blinded | 1 | 0.00 | −0.10, 0.10 | 1.000 | – | – | |
| Double-blinded | 7 | −0.21 | −0.30, −0.12 | <0.001 | 7.6 | 0.370 | |
| Triple-blinded | 4 | −0.36 | −0.55, −0.16 | <0.001 | 0.0 | 0.819 | |
| Type of diabetes | 0.637 | ||||||
| T2DM | 8 | −0.27 | −0.48, −0.05 | 0.014 | 54.9 | 0.030 | |
| Others | 4 | −0.21 | −0.34, −0.07 | 0.003 | 24.5 | 0.264 | |
| Type of intervention | 0.113 | ||||||
| Saffron | 7 | −0.15 | −0.28, −0.03 | 0.018 | 57.5 | 0.028 | |
| Crocin | 5 | −0.38 | −0.62, −0.13 | 0.002 | 39.3 | 0.159 | |
| Form of intervention | 0.168 | ||||||
| Tablet | 7 | −0.33 | −0.49, −0.18 | <0.001 | 9.9 | 0.353 | |
| Capsule | 3 | −0.22 | −0.67, 0.23 | 0.340 | 0.0 | 0.855 | |
| Others | 2 | −0.10 | −0.29, 0.09 | 0.291 | 91.6 | 0.001 | |
| Dose of intervention (mg/day) | 0.001 | ||||||
| ≤30 | 9 | −0.26 | −0.36, −0.15 | <0.001 | 19.4 | 0.271 | |
| >30 | 3 | −0.01 | −0.11, 0.08 | 0.817 | 0.0 | 0.530 | |
| Duration of intervention (weeks) | 0.042 | ||||||
| <12 | 4 | −0.10 | −0.26, 0.07 | 0.242 | 74.9 | 0.008 | |
| ≥12 | 8 | −0.32 | −0.46, −0.18 | <0.001 | 0.0 | 0.465 | |
| Insulin levels (mU/l) | |||||||
| Study design | 0.004 | ||||||
| Single-blinded | 1 | 0.13 | −0.07, 0.33 | 0.198 | - | - | |
| Double-blinded | 4 | −0.59 | −1.51, 0.34 | 0.213 | 68.1 | 0.025 | |
| Triple-blinded | 2 | 3.13 | 1.15, 5.10 | 0.002 | 3.4 | 0.309 | |
| Type of intervention | 0.783 | ||||||
| Saffron | 5 | 0.01 | −0.28, 0.30 | 0.935 | 68.2 | 0.013 | |
| Crocin | 2 | −0.86 | −7.03, 5.32 | 0.786 | 90.4 | 0.001 | |
| Form of intervention | 0.243 | ||||||
| Tablet | 4 | 0.56 | −1.97, 3.09 | 0.665 | 84.0 | <0.001 | |
| Capsule | 2 | −0.51 | −1.25, 0.23 | 0.175 | 0.0 | 0.588 | |
| Others | 1 | 0.13 | −0.07, 0.33 | 0.198 | – | – | |
| Dose of intervention (mg/day) | 0.849 | ||||||
| ≤30 | 3 | 0.43 | −4.05, 4.92 | 0.850 | 83.4 | <0.001 | |
| >30 | 4 | −0.00 | −0.17, 0.17 | 0.968 | 52.0 | 0.125 | |
| Duration of intervention (weeks) | |||||||
| <12 | 2 | −0.08 | −0.66, 0.50 | 0.787 | 61.6 | 0.107 | 0.694 |
| ≥12 | 5 | 0.42 | −2.02, 2.87 | 0.734 | 79.1 | 0.001 | |
| HOMA-IR | |||||||
| Study design | 0.024 | ||||||
| Double-blinded | 4 | −0.55 | −1.19, 0.09 | 0.093 | 76.1 | 0.006 | |
| Triple-blinded | 2 | 1.04 | −0.19, 2.26 | 0.097 | 48.4 | 0.164 | |
| Type of intervention | 0.498 | ||||||
| Saffron | 4 | 0.07 | −0.51, 0.65 | 0.813 | 69.8 | 0.019 | |
| Crocin | 2 | −0.82 | −3.33, 1.69 | 0.521 | 89.6 | 0.002 | |
| Form of intervention | 0.673 | ||||||
| Tablet | 4 | −0.02 | −1.23, 1.19 | 0.970 | 84.9 | <0.001 | |
| Capsule | 2 | −0.46 | −2.12, 1.19 | 0.582 | 8.9 | 0.295 | |
| Dose of intervention (mg/day) | 0.944 | ||||||
| ≤30 | 4 | −0.27 | −2.38, 1.84 | 0.801 | 85.7 | <0.001 | |
| >30 | 2 | −0.19 | −0.43, 0.04 | 0.100 | 10.4 | 0.291 | |
| Duration of intervention (weeks) | 0.801 | ||||||
| <12 | 1 | −0.28 | −0.54, −0.02 | 0.037 | – | – | |
| ≥12 | 5 | −0.12 | −1.32, 1.08 | 0.841 | 81.0 | <0.001 | |
The random-effects meta-analysis model (DerSimonian-Laird method) was used.