Table 3.
Mediation analysis: Adjusted odds ratio (95% CI) for risk of gestational diabetes in association with waist-to-hip ratio, waist circumference, and markers of insulin resistance, a nested case-control study within the Pregnancy Environment and Lifestyle Study, 2013–2016
| Quartile 1a | Quartile 2 | Quartile 3 | Quartile 4 | Proportion mediated, %b | P for indirect effect | |
|---|---|---|---|---|---|---|
| Waist-to-hip ratio and markers of insulin resistance | ||||||
| Multivariable modelc | ||||||
| Waist-to-hip ratio | 1 (reference) | 1.72 (0.43, 6.91) | 3.27 (0.83, 12.9) | 6.59 (1.78, 24.4) | - | - |
| Multivariable model + insulind | ||||||
| Waist-to-hip ratio | 1 (reference) | 1.36 (0.31, 5.95) | 2.21 (0.49, 9.93) | 4.26 (1.06, 17.2) | ||
| Insulin | 1 (reference) | 3.68 (0.71, 19.0) | 3.69 (0.65, 20.9) | 7.94 (1.44, 43.8) | 9.0 (0.5, 17.5) | 0.037 |
| Multivariable model + HOMA-IRd | ||||||
| Waist-to-hip ratio | 1 (reference) | 1.20 (0.28, 5.24) | 2.39 (0.54, 10.6) | 4.17 (1.03, 16.9) | ||
| HOMA-IR | 1 (reference) | 1.41 (0.32, 6.33) | 3.02 (0.60, 15.2) | 6.09 (1.30, 28.4) | 9.6 (1.0, 18.1) | 0.028 |
| Multivariable model + Adiponectind | ||||||
| Waist-to-hip ratio | 1 (reference) | 1.31 (0.28, 6.04) | 2.72 (0.61, 12.2) | 5.13 (1.21, 21.7) | ||
| Adiponectin | 3.35 (0.87, 12.9) | 1.54 (0.42, 5.63) | 0.53 (0.12, 2.37) | 1 (reference) | 11.1 (0.7, 21.6) | 0.037 |
| Waist circumference and markers of insulin resistance | ||||||
| Multivariable modelc | ||||||
| Waist circumference | 1 (reference) | 1.85 (0.48, 7.16) | 2.98 (0.71, 12.6) | 6.35 (1.07, 37.7) | - | - |
| Multivariable model + insulind | ||||||
| Waist circumference | 1 (reference) | 0.82 (0.17, 3.97) | 1.30 (0.24, 6.92) | 2.43 (0.32, 18.3) | ||
| Insulin | 1 (reference) | 4.95 (0.96, 25.7) | 5.38 (0.89, 32.4) | 12.0 (2.03, 71.4) | 40.0 (8.6, 71.5) | 0.013 |
| Multivariable model + HOMA-IRd | ||||||
| Waist circumference | 1 (reference) | 0.79 (0.16, 3.85) | 1.26 (0.23, 6.77) | 2.06 (0.27, 16.0) | ||
| HOMA-IR | 1 (reference) | 2.22 (0.48, 10.3) | 4.41 (0.79, 24.6) | 9.93 (1.89, 52.1) | 41.1 (6.8, 75.3) | 0.019 |
| Multivariable model + Adiponectind | ||||||
| Waist circumference | 1 (reference) | 1.49 (0.36, 6.26) | 2.68 (0.59, 12.3) | 4.91 (0.77, 31.4) | ||
| Adiponectin | 5.51 (1.45, 21.0) | 2.07 (0.59, 7.24) | 0.76 (0.18, 3.17) | 1 (reference) | 35.4 (7.4, 63.4) | 0.013 |
HOMA-IR, insulin and homeostasis model assessment of insulin resistance.
Quartiles are classified based on values among non-gestational diabetes controls.
Proportion mediated on a risk difference scale was calculated as the indirect effect attributed to the particular biomarker divided by the total effect.
Adjusted for prepregnancy body mass index, family history of diabetes, previous gestational diabetes, and pre-existing hypertension.
Adjusted for covariates in the multivariable model and insulin, HOMA-IR, or adiponectin at 16519 weeks of gestation, respectively.