Relationship between urinary albumin excretion and glomerular filtration rate in normotensive, nonproteinuric patients with type 2 diabetes mellitus.
OBJECTIVE
In patients with type 2 diabetes mellitus, the relationship between glomerular filtration rate (GFR) and urinary albumin excretion remains an unresolved issue. In order to investigate the early renal function abnormalities, GFR and urinary albumin excretion were assessed, and their relationship was examined in normotensive patients with type 2 diabetes mellitus.


METHODS
In a cross-sectional study of 85 nonhypertensive Japanese patients with type 2 diabetes mellitus not showing overt proteinuria, the GFR was measured using (99m)Tc-diethylenetriamine pentaacetate renography. Fifty-one diabetic patients lacked microalbuminuria (albumin excretion <30 mg/day), while 34 patients showed microalbuminuria (between 30 and 300 mg/day). Fifteen healthy subjects served as controls.


RESULTS
The three groups were well matched with regard to gender, age, and body mass index. The GFR in microalbuminuric patients (134 +/- 23 ml/min/1.48 m(2)) was significantly higher than in patients without microalbuminuria (108 +/- 21 ml/min/1.48 m(2)) and in controls (109 +/- 18 ml/min/1.48 m(2); p < 0.0001). In type 2 diabetic patients, the GFR positively correlated with the logarithmically transformed urinary albumin excretion. Multiple regression analysis showed that the urinary albumin excretion was significantly and independently affected by GFR (beta = 0.548), duration of diabetes (beta = 0.297), and systolic blood pressure (beta = 0.232; R(2) = 0.409; p < 0.0001).


CONCLUSIONS
It is suggested that one of the mechanisms underlying increased urinary albumin excretion in early nephropathy in normotensive type 2 diabetes is glomerular hyperfiltration.
Taniwaki
H
H
Second Department of Internal Medicine, Osaka City University Medical School, Osaka, Japan.
Ishimura
E
E
Emoto
M
M
Kawagishi
T
T
Matsumoto
N
N
Shoji
T
T
Okamura
T
T
Inaba
M
M
Nishizawa
Y
Y
D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000000981:diagnostic imaging / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D016284:Technetium Tc 99m Pentetate
D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate