Factors affecting the progression of renal dysfunction and the importance of salt restriction in patients with type 2 diabetic kidney disease

Abstract

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).

Conclusion: 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.

Keywords: Annual Ccr decline; Salt intake; Salt restriction; Type 2 diabetic kidney disease; Urinary protein excretion.