H19 and polycystic ovary syndrome: Additionally, combined sitagliptin and metformin therapy upregulated H19 expression by inhibiting the PI3K/AKT-DNMT1 pathway, which, in turn, reduced apoptosis and IR in PCOS model cells and ameliorated hormonal imbalances, ovarian polycystic alterations, and IR in a PCOS rat model [61].