OBJECTIVES: Women with Gestational Diabetes Mellitus (GDM) have six times higher risk of developing Diabetes Mellitus (DM) type 2 compared to women who don’t have GDM. The purpose of this study was to evaluate the protective effects of breast-feeding on development of DM in women with GDM. METHODS: This was a cross sectional study where a secondary database analysis was done using National Health and Nutrition Examination Survey (NHANES) data 2007-2008, 2009-2010 and 2011-2012. Females 20 to 75 years with at least one live birth were included. Chi-square-test compared differences between categorical variables and t-test examined differences in the means for continuous variables. Unadjusted-odds-ratio was calculated using logistic regression to examine breastfeeding as an effect modifier in the association between GDM and DM. Model was adjusted for age, BMI, race/ethnicity, income, education, age at DM and number of live births. Sample weights and the stratification and clustering of the design were incorporated to obtain proper estimates. RESULTS: The final analytic sample consisted of 6503 participants. Percentage of GDM women who breast-fed seemed higher than women without GDM (64.6 % vs. 44.9%). Among women who breastfed, the odds ratio for developing DM in women with GDM was 3.3 (95% CI 2.3, 4.9) compared to those without GDM while, in women who never breastfed, the odds ratio was 3.9 (95% CI 2.3, 6.6). After adjusting for age, BMI, race/ethnicity, education and number of live births, OR for the association between DM and GDM was 2.2 (1.4, 3.4) in women who breastfed and 2.8 (1.6, 4.9) in women who didn’t breast feed. CONCLUSIONS: This analysis found that there’s potential benefit of BF in the prevention of DM among women who had GDM. This result adds to the already known important benefits of BF and more women should be encouraged to BF.