Exploratory Analysis of Serum Oxidized Albumin as a Potential Prognostic Indicator for Diabetic Microvascular Complications: A Retrospective Cohort Pilot Study.

Introduction Oxidative stress is known to play a key role in the pathogenesis of diabetic complications. However, a useful biomarker of oxidative stress has not yet been widely adopted in clinical practice. We explored whether the ratio of serum oxidized albumin (human non-mercaptalbumin, HNA) to total albumin (HNA%) is associated with the five-year prognosis of diabetic complications. Methods In this single-center, retrospective cohort pilot study, we evaluated participants with diabetes who had been hospitalized at baseline and regularly followed up as outpatients. We measured the HNA% at baseline and at a five-year follow-up and assessed the development or progression of diabetic complications. We examined the relationship between baseline HNA% and changes in diabetic complications. Results In participants with simple diabetic retinopathy at baseline, lower baseline HNA% was associated with shorter duration of diabetes and with five-year improvement of retinopathy, irrespective of follow-up glycated hemoglobin levels (25.46% vs. 33.71%, p = 0.021). Additionally, in the overall cohort and in the subgroup with baseline chronic kidney disease (CKD) stage G2, baseline HNA% above the cutoff value was associated with increased risk of CKD progression (overall: RR 1.61, p = 0.042, stage G2 only: RR 1.83, p = 0.047). Regarding macrovascular complications, follow-up HNA%, but not baseline HNA%, was related to their development. Conclusions These exploratory findings suggest that HNA% may have potential as an indicator of the five-year prognosis of diabetic retinopathy and diabetic kidney disease. Further prospective studies are warranted to validate these findings.