Type 2 diabetes in women after a diagnosis of gestational diabetes: understanding uptake to screening, progression rates and costs, using evidence synthesis methodologies

This project comprises a comprehensive investigation of the subsequent risk of type 2 diabetes mellitus (T2DM) and other health complications, in women with a history of gestational diabetes mellitus (GDM), and additionally considers the cost-effectiveness of an intervention to delay or prevent T2DM using a decision model framework. First, a systematic review and meta-analysis was carried out to estimate the risk of developing T2DM in women with GDM. This study found that the risk is higher than previously observed, with these women having a nearly tenfold greater risk of developing T2DM compared to those who had a normoglycaemic pregnancy. Two further projects were carried out using data from the Clinical Practice Research Datalink (CPRD); one estimated post-partum screening attendance rates and potential determinants in the UK, and the other assessed the risk of developing T2DM, hypertension, recurrent GDM, and depression, in a population of women with prior GDM. Regarding screening attendance, this study found that while most women with GDM received at least one glucose screening test within the first 5 years post-partum, fewer than a quarter received on average one test per year of follow-up, as recommended by UK guidelines. The study additionally identified that older age at GDM diagnosis, polycystic ovary syndrome, prescribed medication for GDM, and living in England, were associated with a greater likelihood of screening attendance. In terms of the risk of long-term health conditions, the subsequent study found that the risk of health complications in women with GDM differed by ethnicity and socio-economic status. Finally, the last project of this thesis was a Markov decision model that assessed the cost-effectiveness of intervening to prevent/delay T2DM. The findings of this study suggest that delivering an intervention to reduce risk of progressing to T2DM would be highly cost-effective.