PPARG and gestational diabetes: However, a meta-analysis of 2858 patients with gestational diabetes mellitus (GDM) and 6890 controls from nine published case–control studies demonstrated a protective effect of carrying the minor G allele of the rs180128 polymorphism in the PPARG gene (OR = 0.89, 95% CI: 0.77–1.04, p = 0.015).