XDH and diabetes mellitus: Two recent trials, Preventing Early Renal Loss in Diabetes (PERL) and A randomized Controlled trial of slowing of Kidney Disease progression From the Inhibition of Xanthine oxidase (CKD-FIX), did not find evidence that allopurinol slowed CKD progression (Badve et al., 2020; Doria et al., 2020), thus the benefit of allopurinol for renal function is currently unclear.