The objective of the present study was to investigate the predictive value of islet cell antibodies (ICA) and insulin autoantibodies (IAA) for development of diabetes in women with previous gestational diabetes (GDM). Two hundred and forty-one previous diet-treated GDM patients and 57 women without previous GDM were examined 2-11 years after the index pregnancy. In subgroups, plasma from the diagnostic OGTT during index pregnancy was analysed for ICA and IAA. Among the previous GDM patients, 3.7% had developed Type 1 diabetes and 13.7% Type 2 diabetes. Four (2.9%) of the 139 GDM patients tested for ICA were ICA-positive and three of these had Type 1 diabetes at follow-up, as well as three ICA-negative patients. The sensitivity, specificity, and predictive value of ICA-positivity for later development of diabetes were 50%, 99%, and 75%, respectively. None of the women was IAA-positive during pregnancy. In conclusion, the majority of the patients with GDM did not show evidence of ongoing autoimmune destruction of the beta cells during the index pregnancy. However, ICA-positive GDM patients had a high risk of developing Type 1 diabetes later in life.