Severity of glomerulopathy predicts long-term urinary albumin excretion rate in patients with type 1 diabetes and microalbuminuria.
OBJECTIVE
To investigate whether the degree of glomerular structural lesions in young patients with type 1 diabetes and microalbuminuria was associated with urinary albumin excretion rate (AER) 6 years later and whether the AER level was influenced by blood glucose control, blood pressure, or glomerular filtration rate (GFR).


METHODS
There were 17 young adults with type 1 diabetes and microalbuminuria, 8 men and 9 women with mean age 20 years (95% CI: 18-22) and duration of diabetes of 11 years (10-13), who participated in a 6-year prospective study. Kidney biopsies (measurements of basement membrane thickness [BMT] and mesangial and matrix volume fractions) and GFR were performed at baseline. AER and HbA1c were measured at least three times a year and blood pressure once a year.


RESULTS
In a multivariate analysis, baseline BMT and mean 6-year HbA1c contributed significantly to AER at the end of the study (R2 = 0.69, P < 0.01). When mesangial volume fraction replaced BMT as the independent variable, this parameter and AER at baseline predicted the AER at 6 years (R2 = 0.55, P < 0.55). Mesangial volume fraction and BMT (in separate analysis) contributed significantly to change in AER during the study. During the study, neither AER (30 micrograms/min [19-40] to 16 micrograms/min [7-90]) nor blood pressure (96 mmHg [92-102] to 95 mmHg [91-98]) changed significantly in the group. However, HbA1c was reduced from 10.3 (9.6-11.0) to 8.4% (7.8-9.1) (P < 0.01).


CONCLUSIONS
In young patients with microalbuminuria, the long-term urinary AER was predicted by the degree of glomerular structural changes and associated with blood glucose control, but not with blood pressure or GFR.
Bangstad
H J
HJ
Aker Diabetes Research Center, Aker University Hospital, Oslo, Norway. hj.bangstad@ah.telia.no
Osterby
R
R
Hartmann
A
A
Berg
T J
TJ
Hanssen
K F
KF
D000293:Adolescent; D000328:Adult; D000419:Albuminuria; D001485:Basement Membrane / Q000473:pathology; D015415:Biomarkers / Q000652:urine; D001794:Blood Pressure; D003922:Diabetes Mellitus, Type 1 / Q000473:pathology* / Q000503:physiopathology / Q000652:urine*; D003928:Diabetic Nephropathies / Q000473:pathology* / Q000503:physiopathology / Q000652:urine*; D005260:Female; D005919:Glomerular Filtration Rate; D005920:Glomerular Mesangium / Q000473:pathology; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007678:Kidney Glomerulus / Q000473:pathology*; D008297:Male; D015999:Multivariate Analysis; D013997:Time Factors
D015415:Biomarkers; D006442:Glycated Hemoglobin