Table 2.
Subgroup analysis of the included studies of circulating adiponectin and prediabetes
| Characteristic | No. participants | No. participants | Random effects WMD (95% CI) | P-value | Heterogeneity | |
|---|---|---|---|---|---|---|
| I ² (%) | P-value | |||||
| All studies | 41,841 | 18 | –1.694 (–2.151, –1.237) | <0.001 | 89.9 | <0.001 |
| Region | ||||||
| Asia | 41,160 | 14 | –1.412 (–1.770, –1.053) | <0.001 | 78.2 | <0.001 |
| Europe | 528 | 5 | –1.937 (–2.745, –1.128) | <0.001 | 3.7 | 0.385 |
| USA | 153 | 2 | –2.157 (–5.921, 1.607) | 0.261 | 58.6 | 0.120 |
| Sample size | ||||||
| <50 | 161 | 6 | –1.144 (–2.475, 0.187) | 0.092 | 30.3 | 0.208 |
| 50–100 | 495 | 6 | –2.103 (–3.266, –0.941) | <0.001 | 48.4 | 0.084 |
| >100 | 41,185 | 9 | –1.679 (–2.235, –1.122) | <0.001 | 95.5 | <0.001 |
| Age (years) | ||||||
| <50 | 40,947 | 12 | –1.571 (–2.135, –1.007) | <0.001 | 93.9 | <0.001 |
| 50–60 | 347 | 5 | –1.715 (–3.016, –0.414) | 0.010 | 62.2 | 0.032 |
| >60 | 464 | 3 | –2.204 (–3.207, –1.201) | <0.001 | 0.0 | 0.767 |
| NR | 83 | 1 | –2.461 (–4.619, –0.303) | 0.025 | ||
| HOMA-IR ratio | ||||||
| <1.36 | 298 | 1 | –2.200 (–3.751, –0.649) | 0.005 | ||
| 1.36−1.7 | 203 | 4 | –1.189 (–2.102, –0.276) | 0.011 | 3.6 | 0.375 |
| 1.71−2.12 | 131 | 3 | –1.754 (–2.888, –0.621) | 0.002 | 0.0 | 0.594 |
| >2.12 | 270 | 4 | –2.955 (–4.103, –1.806) | <0.001 | 7.8 | 0.354 |
| NR | 40,878 | 9 | –1.539 (–2.128, –0.951) | <0.001 | 95.5 | <0.001 |
| BMI | ||||||
| <25 | 40,262 | 6 | –1.394 (–1.846, –0.943) | <0.001 | 88.9 | <0.001 |
| 25–30 | 1,012 | 7 | –1.587 (–2.834, –0.340) | 0.013 | 87.4 | <0.001 |
| >30 | 440 | 7 | –1.894 (–2.932, –0.857) | <0.001 | 49.1 | 0.067 |
| NR | 127 | 1 | –1.610 (–2.546, –0.674) | 0.001 | ||
| Quality score | ||||||
| <7 | 805 | 10 | –2.129 (–3.099, –1.158) | <0.001 | 69.6 | 0.001 |
| ≥7 | 41,036 | 11 | –1.365 (–1.716, –1.015) | <0.001 | 79.6 | <0.001 |
| Method | ||||||
| ELISA | 41,042 | 14 | –1.595 (–1.989, –1.202) | <0.001 | 79.8 | <0.001 |
| RIA | 376 | 4 | –2.001 (–3.622, –0.381) | 0.015 | 79.3 | 0.002 |
| Others | 423 | 3 | –1.051 (–1.655, –0.446) | 0.001 | 0.0 | 0.398 |
| Blood sample | ||||||
| Serum | 41,129 | 13 | –1.374 (–1.754, –0.994) | <0.001 | 77.9 | <0.001 |
| Plasma | 712 | 8 | –2.130 (–3.103, –1.158) | <0.001 | 81.0 | <0.001 |
| Sex | ||||||
| Male | 26,211 | 5 | –1.071 (–1.444, –0.698) | <0.001 | 20.9 | 0.281 |
| Female | 14,600 | 4 | –2.178 (–3.384, –0.971) | <0.001 | 92.5 | <0.001 |
BMI, body mass index
CI, confidence interval
ELISA, enzyme-linked immunosorbent assay
HOMA-IR ratio, mean values of homeostatic model assessment of insulin resistance in prediabetes patients to controls in a single study
NR, not reported
RIA, radioimmunoassay
WMD, weight mean difference.