Gestational diabetes increases a woman's risk of developing type 2 diabetes. In 2011, Australia started the first National Gestational Diabetes Register (NGDR). The register aims to improve risk awareness, promote diabetes prevention, and encourage regular diabetes screening. This study aimed to identify postnatal diabetes prevention activity and the association of NGDR awareness with that activity in a nationally representative sample of Australian women after a pregnancy with gestational diabetes. An anonymous, cross-sectional, online survey of women previously diagnosed with gestational diabetes and aged 18 years or over was run from June to November 2014. Of 8860 women invited from a stratified NGDR sample, 966 participated (response rate 13%). Postnatal screening rate was 73%. Only 47% of respondents reported receiving NGDR information postnatally. Log-binomial regression demonstrated an association with women reporting receiving NGDR information and being at intermediate risk of developing type 2 diabetes (relative ratio [RR] 1.307, 95% CI 1.030, 1.660) and at higher disadvantage (RR 1.501, 95% CI 1.080, 2.080). Postnatal screening rates, total diabetes risk perception and lifestyle risk factors were not significantly different between those recalling or not recalling receiving NGDR information. The reach and impact of NGDR information alone are limited. Women's engagement with the NGDR was not associated with better lifestyle, greater postnatal screening or higher risk perception. System-level integration is needed for improved NGDR functioning and further improvements should yield enhanced diabetes prevention efforts when primary care ties are strengthened.