The broad goal of this study is to understand the mechanisms by which Vitamin D receptor activation leads to changes in insulin signaling in advanced uremia. We hypothesize that 1,25-Dihydroxyvitamin D3 deficiency due to advanced chronic kidney disease leads to insulin resistance and that administration of a vitamin D3 analog will restore insulin sensitivity in End Stage Renal Disease patients.

Inclusion Criteria:

• CKD and receiving hemodialysis for ≥ 3months
• Kt/V ≥ 1.2
• ≥ 18 years of age
• Medically stable
• AVF or PTFE dialysis access
• No acute inflammatory disease within 4 weeks prior to the study
• On stable dose of Paricalcitol for 4 weeks prior to the study
• iPTH value between 150 - 1500 within the past 3 months
• Ca < 10.5
• PO4 < 10

Exclusion Criteria:

• Pregnancy
• Intolerance to the study medication
• Severe, unstable, active, or chronic inflammatory disease (active infection, active connective tissue disorder, active cancer, HIV, liver disease)
• Type 1 Diabetes mellitus
• Uncontrolled Type 2 Diabetes mellitus (HbA1c > 10)
• Hospitalization within 1 month prior to the study
• Malfunctioning arterial-venous vascular access (recirculation and/or blood flow < 250 ml/min)
• Presence of hemodialysis catheter
• Patients receiving steroids and/or other immunosuppressive agents (> 10 mg prednisone qd)
• BMI < 25 and > 45