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Renal outcomes in patients with type 1 diabetes and macroalbuminuria
Ian H de Boer1, Maryam Afkarian2, Tessa C Rue3
1Division of Nephrology and Kidney Research Institute and deboer@u.washington.edu.
Abstract:
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 incident macroalbuminuria during the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study. One hundred fifty-nine participants developed incident macroalbuminuria and were subsequently followed for a median duration of 9 years (maximum of 25 years). At the time of macroalbuminuria 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 m(2). 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 system inhibitors. The cumulative incidence of impaired GFR (sustained eGFR<60 ml/min per 1.73 m(2)) 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 kidney disease. However, through at least 10 years of follow-up, AER could often be controlled, and GFR frequently remained in the normal range.
Insights
In type 1 diabetes, macroalbuminuria (high urine albumin levels) often doesn't lead to irreversible kidney damage. Many patients can reduce albumin excretion and maintain normal kidney function over time.
Area of Science:
- Nephrology
- Endocrinology
- Diabetology
Background:
- Macroalbuminuria (urine albumin excretion rate [AER] ≥300 mg/d) in type 1 diabetes has been viewed as a marker of irreversible kidney damage.
- This study investigates long-term renal outcomes following the onset of macroalbuminuria in type 1 diabetes patients.
Purpose of the Study:
- To examine the long-term renal outcomes of individuals with type 1 diabetes who developed incident macroalbuminuria.
- To assess the rates of albuminuria reduction and kidney function decline over time.
Main Methods:
- Analysis of 159 participants from the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study who developed macroalbuminuria.
- Follow-up for a median of 9 years (up to 25 years) to track urine albumin excretion rate (AER) and estimated glomerular filtration rate (eGFR).
Main Results:
- 52% of participants achieved sustained AER <300 mg/d within 10 years, often with renin-angiotensin system inhibitors.
- 32% experienced impaired GFR (eGFR <60 ml/min/1.73 m²) 10 years post-diagnosis, with 16% developing end-stage renal disease (ESRD).
- Lower hemoglobin A1c, blood pressure, and regression of albuminuria were linked to a reduced risk of impaired GFR.
Conclusions:
- While macroalbuminuria indicates high risk for progressive kidney disease in type 1 diabetes, kidney function can often be preserved.
- Effective management strategies can lead to albuminuria control and maintenance of normal GFR in many patients over a decade.
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