Gestational diabetes & diabetes in pregnancy
Association of gestational thyroid function and thyroid autoimmunity with gestational diabetes: a systematic review and individual participant meta-analysis
Pooled result · GDMResult — go to the resultAdjusted odds ratio 1.52 95% CI 1.17–1.98Authors' conclusion
A lower FT4 concentration and isolated hypothyroxinaemia during pregnancy are associated with a higher risk of gestational diabetes. Our results challenge the long-standing notion that subclinical hypothyroidism or thyroid autoimmunity are risk factors for gestational diabetes and support both the risk profile for gestational thyroid dysfunction and ongoing efforts on optimisation of treatment targets for pregnant people taking levothyroxine. Follow-up studies are required to establish to what extent levothyroxine initiation or dose adjustments can affect insulin resistance and antihyperglycaemic therapies during pregnancy.
Study context
- Population
- Pregnant participants of prospective population-based cohorts, excluding multiple pregnancies, pre-existing thyroid disease or DM, medications affecting thyroid or glucose levels, infertility treatment, miscarriage or stillbirth
- Participants
- 63,548 participants25 cohorts
- Comparison
- Gestational thyroid function and autoimmunity vs euthyroidism
- Isolated hypothyroxinaemian = 1,113
- Euthyroidismn = 44,787reference
- Outcome
- Presence of GDM as defined in individual cohorts
Methodological detailspreregistered protocol, generalised linear mixed-effects regression, adjusted for maternal age, BMI, smoking, parity, ethnicity, fetal sex, gestational age at blood sampling, 638 published studies identified; 21 studies based on 17 cohorts met inclusion criteria; 11 provided individual participant data, 14 cohorts added via personal contacts and open invitations
- Preregistered protocol
- Generalised linear mixed-effects regression
- Adjusted for maternal age, BMI, smoking, parity, ethnicity, fetal sex, gestational age at blood sampling
- 638 published studies identified; 21 studies based on 17 cohorts met inclusion criteria; 11 provided individual participant data, 14 cohorts added via personal contacts and open invitations
Pooled result
GDM
Adjusted odds ratio
1.52
95% CI 1.17–1.98
P = 0.0017
Events by group
As reported in the abstract
- Lower free T4 (FT4) associated with higher GDM risk (non-linear)
- P < 0.0001
- Higher free T3 (FT3) associated with higher GDM risk, aOR
- 1.18 (95%CI 1.10-1.28), p<0.0001
- Higher FT3-to-FT4 ratio associated with higher GDM risk (non-linear)
- P < 0.0001
Further pooled results
- I2 for primary analyses (low to moderate heterogeneity)
- 0-43%
- Funnel plot for overt hyperthyroidism indicated possible publication bias
- P = 0.049
Original publication
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