Table 1.
Characteristics of the included studies in the systematic review and meta-analysis
| Study | Country | Study design | Participant | Gender | Sample size (IG/CG) |
Trial duration (week) |
Means Age | Means BMI | Intervention | Dose | CG | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IG | CG | IG | CG | ||||||||||
| Mahboobi et al. (2014) | Iran | RCT, PC, parallel, DB | Prediabetic |
M & F (NR) |
55 (28/27) |
8 | 51.03 ± 1.37 | 50.36 ± 1.32 | 28.87 ± 0.8 | 29.7 ± 0.8 |
Probiotics (multi-strain) |
500 mg/day | Placebo |
| Kassaian et al. (2018) (A) | Iran | RCT, PC, parallel, DB | Prediabetic |
M & F (23, 21) |
44 (30/14) |
24 | 52.97 ± 6.8 | 52.97 ± 5.9 | 29.1 ± 2.9 | 30.4 ± 3.2 | Synbiotics | 6 g (1 × 109 CFU for each) + inulin-based prebiotic | Placebo |
| Kassaian et al. (2018) (B) | Iran | RCT, PC, parallel, DB | Prediabetic |
M & F (18, 23) |
41 (27/14) |
24 | 52.9 ± 6.3 | 52.97 ± 5.9 | 29.6 ± 3.5 | 30.4 ± 3.2 |
Probiotics (multi-strain) (Bifidobacterium spp.) |
6 g/day (1 × 109 CFU for each) | Placebo |
| Kassaian et al. (2019) (A) | Iran | RCT, PC, parallel, DB | Prediabetic |
M & F (18, 23) |
41 (27/14) |
24 | 52.9 ± 6.3 | 52.97 ± 5.9 | 29.6 ± 3.5 | 30.4 ± 3.2 |
Probiotics (multi-strain) (Bifidobacterium spp.) |
6 g/day (1 × 109 CFU for each) | Placebo |
| Kassaian et al. (2019) (B) | Iran | RCT, PC, parallel, DB | Prediabetic |
M & F (23, 21) |
44 (30/14) |
24 | 52.97 ± 6.8 | 52.97 ± 5.9 | 29.1 ± 2.9 | 30.4 ± 3.2 | Synbiotics | 6 g (1 × 109 CFU for each) + inulin-based prebiotic | Placebo |
| Tay et al. (2020) | New Zealand | RCT, PC, parallel, DB | Prediabetic |
M & F (8, 18) |
26 (15/11) |
12 | 52.9 ± 8.7 | 54.1 ± 6.4 | 34.7 ± 4.9 | 33.6 ± 3.7 |
Probiotic (L. Rhamnosus) |
6 × 109 CFU | Placebo |
| Oh et al. (2021) | Korea | RCT, PC, parallel, DB | Prediabetic |
M & F (29, 8) |
37 (20/17) |
8 | 53.55 ± 10.18 | 56.4 ± 11.57 | 25.03 ± 1.92 | 25.25 ± 3.14 |
Probiotic (L. Rhamnosus) |
Once per day (4 × 109 CFU/capsule) | Placebo |
| Barthow et al. (2022) | New Zealand | RCT, PC, parallel, DB | Prediabetic | M & F (36, 41) |
77 (38/39) |
24 | 60.4 ± 10.66 | 59.9 ± 8.66 | 30.9 ± 5.3 | 29.9 ± 6.6 | Probiotics | 6 × 109 (CFU/day) | Placebo |
| AkbariRad et al. (2023) | Iran | RCT, PC, parallel, DB | Prediabetic |
M & F (20, 50) |
70 (35/35) |
12 | 44 ± 8.66 | 43.06 ± 8.53 | 30.74 ± 3.56 | 31.41 ± 3.97 | Synbiotics | 500 mg/day | Placebo |
IG intervention group, CG control group, RCT randomized clinical trial, PC placebo control, SB single-blind, DB double-blind, M male, F female, CFU Colony-forming unit