Hyperglycaemia in pregnancy: Outcomes and diagnostic accuracy of combined modalities.

Abstract

The prevalence of diabetes mellitus (DM) during pregnancy is rising globally, yet data on gestational diabetes mellitus (GDM) in South Africa remain limited. This study retrospectively analysed glycaemic characteristics and outcomes in 298 women with pre-gestational DM and hyperglycaemia first detected in pregnancy (HFDP) between August 2019 and January 2021. Hyperglycaemic disorders were attributed to GDM (39.6%, n = 118), followed by type 2 diabetes (T2DM) (29.2%, n = 87), overt DM (22.1%, n = 66) and type 1 diabetes (T1DM) (9.1%, n=27). Significant risk factors for GDM included family history, obesity, poor obstetric history, and a previous history of macrosomia in pregnancy. Glycated haemoglobin (HbA1c) levels at booking were highest in women with pre-gestational DM (8.8% in T1DM and 7.8% in T2DM). A combination of HbA1c ≥ 5.75% and fasting plasma glucose (FPG) of 5.1-6.9 mmol/L was the most accurate method for diagnosing GDM, with an area under the curve (AUC) of 0.93. Postpartum follow-up using an oral glucose tolerance test (OGTT) revealed that 21% of women with GDM developed DM, while 53% had an impaired glucose tolerance (IGT). However, only 48% of those with GDM were followed up postpartum, highlighting the significant challenge of loss to follow-up. These findings emphasise the growing prevalence of HFDP and the elevated risk of postpartum DM, highlighting the need for improved follow-up care to mitigate long-term complications. Additionally, the combination of FPG and HbA1c ≥ 5.75% shows promise for enhancing GDM diagnosis and screening protocols, particularly in developing countries. Further research is needed to validate these findings and assess their broader applicability.