Table 4.
Summary data in studies on circulating IGF-I and IGF-II levelsa in GDM and control (euglycemic) pregnancies.
| Study type* | References | Country | Specimen | Assay | GA. | GDM (ng/ml)a | Controls (ng/ml)a | GDM vs. control difference (95% CI)c | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Method | Weeks | N | Mean | SD | N | Mean | SD | |||||
| IGF-I | ||||||||||||
| PC | Luo et al. (22) | Canada | Plasma | ELCA | 24–28 | 27 | 285.6 | 109.5 | 280 | 200.4 | 80.4 | 85.20 (42.84, 127.56) |
| PC | Luo et al. (22) | Canada | Plasma | ELCA | 32–35 | 27 | 403.6 | 171.8 | 279 | 307.0 | 123.6 | 96.60 (30.19, 163.01) |
| PC | Hayati et al. (24) | Malaysia | Serum | ELISA | 28 | 25 | 300 | 90 | 50 | 254 | 127 | 46.00 (2.85, 89.15) |
| PC | Hayati et al. (24) | Malaysia | Serum | ELISA | 36 | 25 | 389 | 85 | 50 | 302 | 106 | 87.00 (42.58, 131.42) |
| PC | Matuszek et al. (19) | Poland | Serum | ELISA | 24–28 | 46 | 152.6 | 87.5 | 21 | 120.8 | 58.8 | 31.75 (−3.91, 67.41) |
| PC | Hughes et al. (29) | Britain | Serum | RIA | 31–40 | 20 | 416 | 92 | 29 | 296 | 83 | 120.00 (69.62, 170.38) |
| PC | Ramirez et al. (20) | USA | Serum | ELISA | 26 | 30 | 173.96 | 65.04 | 42 | 197.0 | 191.1 | −23.04 (−85.34, 39.26) |
| NCC | Zhu et al. (27) | USA | Plasma | ELISA | 10–14 | 107 | 180.2 | 64.1 | 214 | 164.9 | 57.4 | 15.27 (0.90, 29.64) |
| NCC | Zhu et al. (27) | USA | Plasma | ELISA | 15–26 | 107 | 217.5 | 92.2 | 214 | 181.9 | 70.3 | 35.61 (15.76, 55.46) |
| NCC | Zhu et al. (27) | USA | Plasma | ELISA | 32–35 | 38 | 335.8 | 579.1 | 45 | 293.1 | 144.8 | 42.78 (−146.13, 231.69) |
| NCC | Zhu et al. (27) | USA | Plasma | ELISA | 37–39 | 51 | 326.5 | 302.0 | 58 | 297.1 | 216.3 | 29.41 (−70.43, 129.25) |
| PC | Grissa et al. (21) | Tunisia | Serum | ELISA | Delivery | 30 | 650.9 | 168.0 | 30 | 414.3 | 100.6 | 236.66 (166.59, 306.73) |
| CC | Lappas (25) | Australia | Plasma& | ELISA | Delivery | 44 | 58.0 | 35.8 | 30 | 57.4 | 25.7 | 0.60 (−13.42, 14.62) |
| CC | Lappas (25) | Australia | Plasma& | ELISA | Delivery | 26 | 55.1 | 40.8 | 36 | 51.8 | 31.2 | 3.30 (−15.40, 22.00) |
| CC | Qian et al. (23) | China | Serum | RIA | Delivery | 20 | 239.85 | 68.9 | 38 | 201.5 | 52.4 | 38.35 (3.86,72.84) |
| NCC | Liao et al. (30) | New Zealand | Serum | ELISA | 20 | 28 | 275.7 | 60.9 | 28 | 218.5 | 58.7 | 50.20 (25.87, 88.53) |
| PC | Qiu et al. (28) | USA | Plasma | ELISA | 13 | 47 | NA | NA | 757 | NA | NA | Categorical data only |
| Meta-Analysisb | ||||||||||||
| GA | <20 weeks | 2 studies | <3 studies | |||||||||
| 20–29 | 6 studies | P <0.001 | 42.12 (28.87, 55.37) | |||||||||
| 30+ | 6 studies | P <0.001 | 98.07 (47.23, 148.90) | |||||||||
| IGF-II | ||||||||||||
| PC | Luo et al. (22) | Canada | Plasma | ELCA | 24–28 | 27 | 864.6 | 164.3 | 280 | 905.0 | 143.2 | −40.40 (−104.6, 23.80) |
| PC | Luo et al. (22) | Canada | Plasma | ELCA | 32–35 | 27 | 983.5 | 244.8 | 279 | 995.7 | 180.4 | −12.20 (−106.93, 82.53) |
| CC | Lappas (25) | Australia | Plasma& | ELISA | Delivery | 44 | 293.7 | 189.0 | 30 | 269.5 | 175.8 | 24.20 (−67.43, 115.83) |
| CC | Lappas (25) | Australia | Plasma& | ELISA | Delivery | 26 | 309.9 | 245.8 | 36 | 267.8 | 210.0 | 42.10 (−86.66, 170 86) |
| NCC | Liao et al. (30) | New Zealand | Serum | ELISA | 20 | 28 | 814.7 | 131.8 | 28 | 836.4 | 100.5 | −21.70 (−83.09, 39.69) |
| Meta-Analysisb | <3 studies | |||||||||||
Some studies reported maternal IGF-I and/or IGF-II data at multiple gestational age windows, and thus occupied multiple data lines in the table.
Study type: PC, Prospective Cohort study; NCC, Nested Case Control study; CC, Case-Control study; NA, not available. GA, gestational age (weeks); ELISA, enzyme-linked immunosorbent assay; ELCA, enzyme-labeled chemiluminescent assay; RIA, radioimmunoassay.
Conversion factor: IGF-I, 1 nmol/L = 7.649 μg/L or ng/ml; IGF-II, 1 nmol/L = 7.469 μg/L or ng/ml.
There was only one study on free IGF-I or free IGF-II (Lappas 2015 study); all other studies are on total IGF-I or total IGF-II; meta-analysis was conducted on total IGF-I or IGF-II in circumstances with ≥3 studies.
The differences with 95% CIs excluding the zero are shown in bold.
The study on free IGF-I or free IGF-II.