Do maternal haemodynamics have a causal influence on treatment for gestational diabetes?

BACKGROUND

Arterial stiffening is believed to contribute to the worsening of insulin resistance, and factors which are associated with needing pharmacological treatment of gestational diabetes (GDM), such as maternal obesity or advanced age, are associated with impaired cardiovascular adaptation to pregnancy. In this observational study, we aimed to investigate causal relationships between maternal haemodynamics and treatment requirement amongst women with GDM.

METHODS

We assessed maternal haemodynamics in women with GDM, comparing those who remained on dietary treatment with those who required pharmacological management. Maternal haemodynamics were assessed using the Arteriograph® (TensioMed Ltd, Budapest, Hungary) and the NICOM® non-invasive bio-reactance method (Cheetah Medical, Portland, Oregon, USA). A graphical causal inference technique was used for statistical analysis.

RESULTS

120 women with GDM were included in the analysis. Maternal booking BMI was identified as having a causative influence on treatment requirement, with each unit increase in BMI increasing the odds of needing metformin and/or insulin therapy by 12% [OR 1.12 (1.02 - 1.22)]. The raw values of maternal heart rate (87.6 ± 11.7 vs. 92.9 ± 11.90 bpm, p = 0.014) and PWV (7.8 ± 1.04 vs. 8.4 ± 1.61 m/s, p = 0.029) were both significantly higher amongst the women requiring pharmacological management, though these relationships did not remain significant in causal logistic regression.

CONCLUSIONS

Maternal BMI at booking has a causal, rather than simply associational, relationship on the need for pharmacological treatment of GDM. No significant causal relationships were found between maternal haemodynamics and the need for pharmacological treatment.

Does treatment modality affect measures of arterial stiffness in women with gestational diabetes?

OBJECTIVE

To investigate whether arterial stiffness (AS) differs between healthy women and women with gestational diabetes mellitus (GDM) managed by different treatment modalities.

METHODS

This was a prospective longitudinal cohort study comparing AS in pregnancies complicated by GDM and low-risk controls. AS was assessed by recording aortic pulse-wave velocity (AoPWV), brachial augmentation index (BrAIx) and aortic augmentation index (AoAIx) using the Arteriograph® at four gestational-age windows: 24 + 0 to 27 + 6 weeks (W1); 28 + 0 to 31 + 6 weeks (W2); 32 + 0 to 35 + 6 weeks (W3) and ≥ 36 + 0 weeks (W4). Women with GDM were considered both as a single group and as subgroups stratified by treatment modality. Data were analyzed using a linear mixed model on each AS variable (log-transformed) with group, gestational-age window, maternal age, ethnicity, parity, body mass index, mean arterial pressure and heart rate as fixed effects and individual as a random effect. We compared the group means including relevant contrasts and adjusted the P-values using Bonferroni correction.

RESULTS

The study population comprised 155 low-risk controls and 127 women with GDM, of whom 59 were treated with dietary intervention, 47 were treated with metformin only and 21 were treated with metformin + insulin. The two-way interaction term of study group and gestational age was significant for BrAIx and AoAIx (P < 0.001), but there was no evidence that mean AoPWV was different between the study groups (P = 0.729). Women in the control group demonstrated significantly lower BrAIx and AoAIx compared with the combined GDM group at W1-W3, but not at W4. The mean difference in log-transformed BrAIx was -0.37 (95% CI, -0.52 to -0.22), -0.23 (95% CI, -0.35 to -0.12) and -0.29 (95% CI, -0.40 to -0.18) at W1, W2 and W3, respectively. The mean difference in log-transformed AoAIx was -0.49 (95% CI, -0.69 to -0.30), -0.32 (95% CI, -0.47 to -0.18) and -0.38 (95% CI -0.52 to -0.24) at W1, W2 and W3, respectively. Similarly, women in the control group also demonstrated significantly lower BrAIx and AoAIx compared with each of the GDM treatment subgroups (diet, metformin only and metformin + insulin) at W1-W3. The increase in mean BrAIx and AoAIx seen between W2 and W3 in women with GDM treated with dietary management was attenuated in the metformin-only and metformin + insulin groups. However, the mean differences in BrAIx and AoAIx between these treatment groups were not statistically significant at any gestational-age window.

CONCLUSIONS

Pregnancies complicated by GDM demonstrate significantly higher AS compared with low-risk pregnancies regardless of treatment modality. Our data provide the basis for further investigation into the association of metformin therapy with changes in AS and risk of placenta-mediated diseases. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.