Visceral Adipose Tissue was Associated with Increased Risk of Insulin Resistance in Lean Polycystic Ovarian Syndrome, Independent with Retinol Binding Protein-4: Jaringan Adiposa Viseral berkaitan dengan Peningkatan Risiko Resistensi Insulin pada Sindrom Ovarium Polikistik dengan Indeks Masa Tubuh Normal, Independen terhadap Retinol Binding Protein-4