AIMS: Women with a history of gestational diabetes mellitus (GDM) are at an increased risk for the future development of type 2 diabetes. Recently, over 65 genetic variants have been confirmed to be associated with diabetes. We investigated whether this genetic information could improve the prediction of future diabetes in GDM women. METHODS: This was a prospective cohort study consisting of 395 GDM women who were followed annually with an oral glucose tolerance test. A weighted genetic risk score (wGRS), consisting of 48 variants, was assessed for improving discrimination (C statistic) and risk reclassification (continuous net reclassification improvement index [NRI]) when added to clinical risk factors. RESULTS: Among the 395 GDM women, 116 subjects (29.4%) developed diabetes during a median follow-up period of 45 months. GDM women who developed diabetes had a significantly higher wGRS than those who did not (9.36 ± 0.92 vs. 8.78 ± 1.07, P < 1.56x10-7). In a complex clinical model adjusted for age, prepregnancy BMI, family history of diabetes, blood pressure, fasting glucose, and fasting insulin concentration, the C statistic marginally improved from 0.741 without the wGRS to 0.775 with the wGRS (P = 0.015). The addition of the wGRS to the clinical model resulted in a modest improvement in reclassification (continuous NRI 0.430 [95% CI 0.218, 0.642], P = 7.0x10-5). CONCLUSIONS: In GDM women who are at high risk of diabetes, the wGRS was significantly associated with the future development of diabetes, and improved prediction over clinical risk factors.