Evaluate the Efficacy and Safety of Once Daily Administration of Atrasentan Tablets (Low and High) Compared to Placebo in Reducing Residual Albuminuria in Type 2 Diabetic Patients With Nephropathy Who Are Treated With the Maximum Tolerated Labeled Dose of a Renin Angiotensin System (RAS) Inhibitor

Prospective, Randomized, Double-Blind, Placebo-Controlled Multicenter Study. The objective of the study is to evaluate the efficacy and safety of once daily administration of atrasentan tablets (low dose and high dose) compared to placebo in reducing residual albuminuria in Type 2 diabetic patients with nephropathy who are treated with the maximum tolerated labeled dose of a Renin Angiotensin System (RAS) inhibitor. If the patient is already receiving a maximum tolerated labeled daily dose of RAS inhibitor and a diuretic, he/she will complete 4 weeks of the Run-in Period on a dose that has not been adjusted. If the patient is currently not receiving a maximum labeled daily dose of a RAS inhibitor then the dose will be titrated up to the maximum tolerated labeled dose over the course of 4 to 8 weeks during the Run-in Period. It is expected that subjects not receiving a diuretic will have a diuretic added or titrated during this period to maximize RAS inhibition. Following titration to the maximum tolerated labeled dose, the patient will complete an additional 4 weeks of Run-In Period on an unchanged doses of RAS inhibitor and diuretics, unless medically contraindicated. The randomization will be stratified based on country where subjects are enrolled into the study, and the Week -1 Urinary Albumin to Creatinine Ratio (UACR) levels (\ 1000 mg/g \[113 mg/mmol\]). Within each stratum, subjects will be randomly assigned in a 1:2:2 ratio to one of the following blinded treatment groups: Group A - Placebo once daily (QD) Group B - low dose atrasentan QD Group C - high dose atrasentan QD After the 12 weeks of study drug treatment, subjects will be followed up to 30 days.