Impact of gestational diabetes on the risk of diabetes following pregnancy among Chinese and South Asian women

Ethnicity and gestational diabetes mellitus (GDM) are both risk factors for the development of type 2 diabetes. However, it is uncertain whether ethnicity modifies the effect of GDM on diabetes risk. We aimed to determine the risk of diabetes following pregnancy with and without GDM for Chinese and South Asian women compared with white women. Using healthcare databases, all 1,050,108 women aged 20-49 with live births between January 1995 and June 2008 in Ontario were identified. They were followed for up to 15 years for the diagnosis of diabetes. The age-standardised prevalences of GDM were 4.1%, 7.1% and 2.9% for Chinese, South Asian and white women, respectively. The cumulative incidence of diagnosed diabetes at the median follow-up time of 7.6 years was 16.5% and 1.8% for Chinese women with and without GDM, 31.8% and 3.6% for South Asian women with and without GDM, and 25.7% and 1.8% for white women with and without GDM. The presence of GDM conferred an increase in the risk for diabetes after pregnancy of more than 13-fold in white women, but only a nine- to tenfold increase among Chinese and South Asian women. Although one-third of South Asian women with GDM were diagnosed with diabetes within 8 years postpartum, the incremental impact of GDM on diabetes risk was not as strong among Chinese and South Asian women as it was among white women.