Probucol in albuminuric type 2 diabetes mellitus patients on renin-angiotensin system blockade

Objective - To determine the effect of probucol on urine albumin excretion in type 2 diabetes mellitus patients with albuminuria using angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Approach and Results - This was a 16-week, phase II, randomized, placebo-controlled, parallel-group study in type 2 diabetes mellitus patients with a urinary albumin/creatinine ratio of ≥300 mg/g using angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, conducted in 17 tertiary referral hospitals. Eligible patients were randomized to probucol 250 mg/d (n=44), probucol 500 mg/d (n=41), and placebo (n=41) groups in a ratio of 1:1:1 after block randomization procedures, keeping the treatment assignment blinded to the investigators, patients, and study assistants. The primary end point was change in the geometric mean of urinary albumin/creatinine ratio from baseline to week 16 (ClinicalTrials.gov identifier NCT01726816). The study was started on November 8, 2012, and completed on March 24, 2014. The least squares mean change±SE from baseline in urinary albumin/creatinine ratio at week 16 was -7.2±639.5 mg/g in the probucol 250 mg/d group (n=43; P=0.2077 versus placebo group), 9.3±587.4 mg/g in the probucol 500 mg/d group (n=40; P=0.1975 versus placebo group), and 259.0±969.1 mg/g in the placebo group (n=41). Although the majority of subjects were on statins, probucol treatment significantly lowered total cholesterol and low-density lipoprotein cholesterol levels. QT prolongation occurred in one and two subjects in control and probucol 250 mg/d groups, respectively. Conclusions - Four months of probucol up to 500 mg/d failed to reduce urinary albumin excretion.