Albumin excretion rate and its relation to kidney disease in non-insulin-dependent diabetes mellitus.

Objective: To estimate the occurrence of increased albumin excretion rate (AER) and its significance as a marker of diabetic kidney disease in non-insulin-dependent diabetic subjects.
Design: Population-based, controlled cross-sectional study.
Setting: A primary health care centre in the city of Tampere, south-west Finland.
Subjects: Consecutive, recently diagnosed (n = 150) and long-term (n = 146) middle-aged non-insulin-dependent diabetic subjects. Matched non-diabetic control subjects (n = 150).
Main Outcome Measures: Albumin excretion rate, fractional AER, microalbuminuria (AER 30-300 mg 24 h-1), clinical nephropathy (AER exceeding 300 mg 24 h-1) and kidney biopsy in diabetic subjects with an AER exceeding 100 mg 24 h-1.
Results: Mean (+/- standard deviation [SD]) 24-h AER was increased in recently diagnosed diabetic subjects, 54 (111) mg, and long-term diabetic subjects, 134 (479) mg, compared to non-diabetic control subjects, 16 (19) mg. The fractional AER was 7.5 (18.3) x 10(-6) in recent diabetic subjects, 53.1 (306.9) x 10(-6) in long-term diabetic subjects and 2.8 (3.7) x 10(-6) in non-diabetic control subjects. Microalbuminuria was found in 8% of non-diabetic subjects, in 29% of recent and in 27% of long-term diabetic subjects. The prevalence of clinical nephropathy was 7% in long-term and 4% in recent diabetic subjects, whilst no non-diabetic subject had nephropathy. In 12 of 16 eligible kidney biopsies, diabetic glomerulosclerosis was found, in four subjects the finding was normal.
Conclusions: The AER is clearly increased in recent non-insulin-dependent diabetic subjects and further increased in diabetic subjects with a mean disease duration of 10 years. An increased AER in non-insulin-dependent diabetic subjects suggests diabetic kidney disease.