Renal outcomes in patients with type 1 diabetes and macroalbuminuria

Macroalbuminuria, defined as urine albumin excretion rate (AER)≥300 mg/d, has long been considered a stage of irreversible kidney damage that leads reliably to GFR loss. We examined the long-term renal outcomes of persons with type 1 diabetes who developed incidentmacroalbuminuria during the Diabetes Control andComplications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study. One hundred fifty-nine participants developed incident macroalbuminuria and were subsequently followed for amedian duration of 9 years (maximumof 25 years).At the timeofmacroalbuminuria diagnosis,mean (SD) age was 37 (9) years, mean (SD) duration of diabetes was 17 (5) years, median AER was 524 mg/d, and mean (SD) eGFR was 108 (20) ml/min per 1.73 m². Ten years after macroalbuminuria diagnosis, the cumulative incidence of a sustained reduction in AER to <300 mg/d was 52%, mostly but not entirely under treatment with renin-angiotensin systeminhibitors. The cumulative incidence of impaired GFR (sustained eGFR<60 ml/ min per 1.73 m²) 10 years after macroalbuminuria diagnosis was 32%, including 16% who developed ESRD. Lower hemoglobin A1c and BP and regression to AER<300 mg/d were associated with reduced risk of developing impaired GFR. In conclusion, people with type 1 diabetes who develop macroalbuminuria are at high risk of progressive kidneydisease.However, through at least 10 years of follow-up,AER could often be controlled, and GFR frequently remained in the normal range.