The Role of the Metabolome in the Development of Gestational Diabetes Mellitus in High-Risk Minority Women: A Causal Investigation

Gestational Diabetes Mellitus (GDM) is the most common pregnancy complication worldwide. However, GDM prevalence is substantially lower in white Europeans (WEs) compared to other ethnicities, especially South Asians (SAs) who experience the highest risk. Globally, healthy diet promotion is the mainstay in GDM prevention, however current guidelines are predominantly based on evidence from WEs. Furthermore, metabolic factors responsible for the disparities in prevalence are unknown but may offer guidance for improved prevention and management. This project aimed to (i) assess the association between diet and GDM across ethnic groups, (ii) determine if distinct metabolic profiles characterise GDM in SAs and WEs, and (iii) evaluate the presence of ethnic-specific causal associations between metabolites and gestational dysglycemia. Aims (ii) and (iii) utilised data from the Born in Bradford cohort (mean gestational age 26.1 weeks). First, through a systematic review of observational and randomised studies, pre-pregnancy diet was found to associate with GDM in WEs, but not in Asians. Secondly, the multivariate analyses of metabolites identified 7 metabolites that were characteristic of GDM in both ethnicities, with an additional 6 characteristic in WEs only. Finally, through Mendelian Randomisation (MR) analyses, 14 metabolites associated with pregnancy dysglycemia in WEs and 11 in SAs. No metabolites were identified in both ethnicities. Cholesterols and fatty acids were the most commonly identified classes identified in WEs and SAs, respectively. This project demonstrated (i) inconsistencies in the association between diet and GDM across ethnicities (ii) distinct metabolic profiles that associate with GDM in WEs and SAs and offers and supports the need for ethnic-specific manage GDM management strategies. In high-risk SAs, fatty acids may be the most important predictors of GDM. Future work should evaluate the role of pre-pregnancy fatty acid intake in GDM development in SAs to aid in the development of culturally tailored dietary interventions.