Protein intake is not associated with progression of diabetic kidney disease in patients without macroalbuminuria.

BACKGROUND: Diabetic kidney disease is an important problem in individuals with diabetes. The effect of dietary protein intake on the renal function of patients with diabetes is controversial. Here, we sought to clarify the association between dietary protein intake and changes in the urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.

METHODS: In this retrospective cohort study, we included 144 patients (70 men, mean ± standard deviation of age 64 ± 10 years, and median (interquartile range) of UAE 15.0 (7.0-38.9) mg/gCr) without an eGFR less than 30 mL/min/1.73 m2 and/or UAE greater than or equal to 300 mg/gCr. Changes in the UAE or eGFR were defined as (logarithms [UAE+1] or eGFR at follow-up minus logarithms [UAE+1] or eGFR at baseline examination)/follow-up duration (years). Habitual protein intake was estimated by a self-administered diet history questionnaire.

RESULTS: The median follow-up duration was 5 years. Protein intake (g/kg ideal body weight/day) was not associated with the change in the UAE (r = -0.130, p = 0.120) or change in the eGFR (r = -0.074, p = 0.381). Multiple linear regression analyses showed that after adjusting for covariates, the patients' protein intake was not associated with change in their UAE (standardized regression coefficient: 0.044, p = 0.732) or change in their eGFR (standardized regression coefficient: 0.250, p = 0.085).

CONCLUSIONS: Dietary protein intake does not influence changes in the UAE or eGFR among patients with type 2 diabetes without macroalbuminuria.