INCLUSION CRITERIA:

1. Patients who have given voluntary written consent to participate in this study prior to conducting Screening Visit procedures;
2. Male and female patients 25 years of age or older with a diagnosis of type 2 diabetes; • If a woman is of childbearing potential (WOCBP) she must agree to use appropriate birth control (double barrier methods, hormonal contraceptives, or intrauterine device)for the duration of the study (WOCBP is defined as all women who are not surgically sterile or are not at least 1 year post-menopausal). All WOCBP must have a negative serum pregnancy test at the Screening Visit;

3. At the Screening Visit, ALL patients must have a history of overt diabetic nephropathy, as defined by the following:

   • A SCr measurement of 1.3 mg/dL to 3.3 mg/dL (women) or 1.5 mg/dL to 3.5 mg/dL (men) inclusive, and
   • A 24-hour urine collection PCR ≥1200 mg/g;
4. Patients must be receiving an ACE-I or an ARB, for at least 3 months prior to the Qualifying Visit (Screening Visit for those patients not entering into the Optional Run-in Period), where the dose of the ACE-I or the ARB is considered appropriate for that patient and has been stable for at least 2 months;
5. Patients must be on stable blood pressure medications for 2 months prior to the Qualifying Visit (Screening Visit for those patients not entering into the Optional Run-in Period), with a seated blood pressure at the Qualifying Visit of ≤160/90 mmHg;

6. At the Qualifying Visit (only applies to those patients who enter into the Optional Run-in Period), the following eligibility parameters must be met in order to be randomized:

   • A SCr measurement within 25% of the SCr measurement at the Screening Visit; and
   • A 24-hour urine collection PCR ≥600 mg/g.

EXCLUSION CRITERIA:

1. Patients with type 1 diabetes;
2. Patients with a diagnosis of chronic renal disease other than diabetic renal disease with or without hypertensive renal disease;
3. Patients receiving a renin inhibitor or an aldosterone antagonist or a combination of an ACE-I and an ARB within 2 months of the Qualifying Visit (Screening Visit for those patients not entering into the Optional Run-in Period);
4. Patients with a history of solid organ transplantation;
5. Patients with a history of myocardial infarction, coronary re-vascularization procedures (including percutaneous transluminal coronary angioplasty), cerebrovascular accident ortransient ischemic attack within 1 month prior to the Screening Visit;
6. Patients with a diagnosis of Class III or IV congestive heart failure at any time (as defined by the New York Heart Association);
7. Patients with a history of neoplastic disease (except basal or squamous cell carcinoma of the skin) within 5 years prior to the Screening Visit;
8. Patients with any history of dialysis within 2 years prior to the Screening Visit;
9. Patients in whom dialysis or renal transplantation is anticipated by their physician within 1 year after the Screening Visit;
10. Patients who used SCr altering drugs within 1 month prior to the Screening Visit;
11. Patients who require systemic immunosuppression therapy for >2 weeks (except for inhalant steroids);
12. Patients with clinically significant liver disease or transaminase (alanine aminotransferase and aspartate aminotransferase) levels >2.5 x upper limit of normal measured at the Screening Visit;
13. Patients with bilirubin levels >1.5 x upper limit of normal measured at the Screening Visit;
14. Patients with a history of allergic or other adverse response to vitamin B preparations;
15. Patients who require >50 mg of vitamin B6 daily;
16. Patients who have a history of dysphasia and swallowing disorders;
17. Patients with a history of hypersensitivity to Pyridorin or any of the excipients in the Pyridorin formulation;
18. Patients who have taken pyridoxamine or any other investigational drug within 30 days prior to the Screening Visit, or have participated in a previous Pyridorin trial or another clinical trial within 30 days prior to the Screening Visit;
19. Patients with a current history of drug or alcohol abuse;
20. Patients unlikely to comply with the study protocol (e.g., an inability and unwillingness to participate in adequate training, an uncooperative attitude, inability to return for follow-up visits, or unlikelihood of completing the study);
21. Women who are lactating, pregnant or intend to become pregnant during the course of the study; and
22. Patients who are employees of NephroGenex or its representatives.