Long-term effects of moderate protein diet on renal function and low-grade inflammation in older adults with type 2 diabetes and chronic kidney disease

Abstract

Objectives: The aim of this study was to determine the long-term effects of a moderate protein diet (MPD) on renal function, low-grade inflammation, and oxidative stress in older adults with type 2 diabetes, which to date are unclear.

Methods: Seventy-four older adults with type 2 diabetes and chronic kidney disease (stage G3b-G4) were enrolled in the study. During the 4-wk baseline period (T0), all patients were asked to follow a normal protein diet regimen, providing 1.1 g/kg daily. Successively, all patients were asked to follow an MPD, for 36 mo, providing 0.7 g/kg daily, for only 6 d/wk. Patients who refused to follow an MPD treatment were included in the control (NPD [normal protein diet] group). During the 36 mo of the study, creatinine clearance, blood urea nitrogen, proteinuria, blood pressure, glycated hemoglobin (Hb)A1c, fat-free mass, low-grade inflammation (interleukin-6 and C-reactive protein) were evaluated monthly and oxidative stress (urinary 8-epiprostaglandin [Epi-PG]F2α) was evaluated every 3 mo.

Results: During T0, mean creatinine clearance, proteinuria, blood urea nitrogen, blood pressure, HbA1c, fat free mass, low-grade inflammation, and oxidative stress were similar in both groups. After 36 mo, a significant reduction in decline of renal function was observed in the MPD group but not in controls (2.4 ± 0.2 versus 5.7 ± 0.5 mL·min·y, respectively; P < 0.05 versus control). Similarly, a significant reduction in proteinuria, serum interleukin-6, serum C-reactive protein, and urinary 8-Epi-PGF2α excretion, was observed in the MPD group (P < 0.05 versus NPD).

Conclusion: In older adults with type 2 diabetes, long-term effects of an MPD regimen are associated with a significant decline of renal function, proteinuria, low-grade inflammation, and oxidative stress without a change in fat-free mass.

Keywords: Decline of renal function; Elderly; FFM; Low-grade inflammation; Moderate protein diet; Proteinuria; Type 2 diabetes; Urinary 8-Epi-PGF 2 alpha.