Higher IL-6 was associated with preeclampsia in women with GDM (OR 1.85; 95% CI 1.17–2.92, per log2) but not in women without GDM (OR 1.25; 95% CI 0.87–1.79, per log2), although this was not significant in the interaction test (p = 0.18). This evidence concerns the gene IL6 and gestational diabetes.