Factors affecting the progression of renal dysfunction and the importance of salt restriction in patients with type 2 diabetic kidney disease.
BACKGROUND
Type 2 diabetic kidney disease (DKD) is the most common cause of end-stage renal failure, and the prevention of its progression has been a topic of discussion.


METHODS
Sixty type 2 DKD patients were retrospectively evaluated for 1 year. Factors independently affecting the annual Ccr decline were examined by multivariable linear regression analysis. Patients were further divided into 2 groups based on their degree of renal function, and between-group differences at study initiation were evaluated.


RESULTS
Ccr values were 21.0 ± 11.8 mL/min/1.73 m(2) at study initiation, and 15.7 ± 10.9 mL/min/1.73 m(2) after 1 year of observation. The multivariable linear regression analysis indicated salt intake (standardized coefficient: -0.34, P = 0.010) and urinary protein excretion (standardized coefficient: -0.33, P = 0.011) to be factors independently affecting the annual Ccr decline. Although decliners (-9.8 ± 4.7 mL/min/1.73 m(2)/year) had a significantly higher salt intake than non-decliners (-1.1 ± 3.8 mL/min/1.73 m(2)/year) at study initiation, this difference disappeared at the end of the study as a result of intensive dietary education. In 21 decliners with an additional year of follow-up, the annual Ccr decline significantly improved from -10.1 ± 5.3 to -5.3 ± 7.4 mL/min/1.73 m(2)/year (P = 0.02).


CONCLUSIONS
Salt intake and urinary protein excretion were associated with annual Ccr decline in type 2 DKD patients. Furthermore, dietary education covering salt intake may have positively affected the change in Ccr.
Department of Nutrition, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Noriko
N
Kanauchi
Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan. su-ooka@hb.tp1.jp.
Susumu
S
Ookawara
Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Kiyonori
K
Ito
Department of Nutrition, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Satsuki
S
Mogi
Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Izumi
I
Yoshida
Division of Endocrinology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Masafumi
M
Kakei
Division of Endocrinology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
San-E
SE
Ishikawa
Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Yoshiyuki
Y
Morishita
Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
Kaoru
K
Tabei
D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use; D003404:Creatinine / Q000652:urine; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy* / Q000473:pathology; D003928:Diabetic Nephropathies / Q000178:diet therapy* / Q000473:pathology; D004039:Diet, Sodium-Restricted; D018450:Disease Progression; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000453:epidemiology / Q000652:urine; D012189:Retrospective Studies; D014563:Urodynamics
D000959:Antihypertensive Agents; D003404:Creatinine
Annual Ccr decline; Salt intake; Salt restriction; Type 2 diabetic kidney disease; Urinary protein excretion