INS and liver dysplastic nodule: Serum urea levels in insulin-treated, vitamin D-treated, and combined insulin and vitamin D-treated groups were significantly lower than that in DN group (39.52 ± 1.40, 47.75 ± 3.65, 32.03 ± 1.83 mg/dL, respectively; P < 0.05) and significantly higher than that in control group (P < 0.05).