Treatment of Diabetic Nephropathy

The study is designed with a screening period, a baseline period and a treatment period. The purpose of screening is to identify eligible subjects and to exclude ineligible subjects. A careful history and physical examination will be conducted to ensure that the subject meets all the inclusion criteria and does not meet any of the exclusion criteria. The screening period lasts from 2 days to 2 months in duration. The baseline period is from 2 - 3 months in duration. During the first baseline visit, there is withdrawal of previously used angiotensin converting enzyme inhibitors or angiotensin receptor antagonists (if any) and the initiation of quinapril 20 mg daily therapy (or irbesartan --150 - 300 mg daily). The subject will then be seen as frequently as determined by the investigator for subject's safety. The purpose of the second baseline visit is to determine safety after the initiation of therapy quinapril 20 mg po per day (or irbesartan 150 - 300 mg per day). The purpose of third baseline visit is to insure that the subject meets all the inclusion and none of the exclusion criteria prior to randomization. In addition, it will be assured that the subject's blood pressure is at a safe level to proceed with randomization and the laboratory and urinary collections will be made. Only those subjects who fulfill all inclusion and none of the exclusion criteria will proceed to randomization. Also, in order to proceed to the randomization phase of the study, the subject must have a blood pressure of less than or equal to 135/85mmHg. The treatment phase will consist of 18 weeks. During the treatment phase, the subject will be followed for safety and efficacy. The subjects will be randomly assigned to COX-2 inhibitor for 6 weeks (1st 6 week cycle), washout 3 weeks, placebo 6 weeks (2nd 6 week cycle), washout 3 weeks or to placebo 6 weeks (1st 6 week cycle), washout 3 weeks, COX-2 inhibitor 6 weeks (2nd 6 week cycle), washout 3 weeks. During baseline and treatment periods, interim visits will be held in order to address blood pressure control or other problems that the patient or the PI deems necessary for protocol adherence.