Pengaruh Suplementasi Vitamin D terhadap Fungsi Sel Beta Pankreas pada Diabetes Melitus Tipe 2. Kajian terhadap SOD, IL-6, Ekspresi PDX-1, dan Resistensi Insulin = Effect of Vitamin D Supplementation on Pancreatic Beta Cell Function in Type 2 Diabetes Mellitus. Study on SOD, IL-6, PDX- 1 Expression, and Insulin Resistance