We assessed the prevalence of gestational diabetes (GDM) in South Africa, including early and late GDM, and investigated insulin sensitivity, 1^st phase insulin secretion, and beta cell function to understand the underlying pathophysiology of glucose metabolism in early and late pregnancy. We also examined the association between HIV and GDM.

We enrolled women with HIV (WWH) and HIV-seronegative women at <18 weeks’ gestation. A 75g oral glucose tolerance test was administered at enrollment (early) and 32-36 weeks’ gestation (late) to diagnose GDM using WHO criteria. Matsuda, Stumvoll, oral disposition index, and glucose sensitivity from Mari models were calculated. Logistic regression models were used to assess the association of HIV with GDM.

Among 1573 (n=668 WWH) participants, median age was 28 years, gestation 13 weeks. Overall, 7.9% had GDM (6.7% WWH, 9.1% HIV-seronegative); of these, 65% had early GDM. Women with early GDM had the lowest Matsuda, Stumvoll, DIo, and glucose sensitivity at enrollment compared to those with late GDM and those without GDM. In adjusted analyses, WWH had lower odds of GDM than HIV-seronegative women [adjusted odds ratio: 0.57, 95% Confidence Interval: 0.38–0.85).

GDM prevalence in South Africa is similar to North America/Europe. Early GDM was diagnosed in a large majority of women who also exhibited features of poorer insulin sensitivity and beta cell function than those diagnosed late in pregnancy or without GDM. WWH had lower GDM risk than HIV-seronegative women. Future studies to understand the implications of early GDM in African populations are warranted.