Background/Aims: Diabetic nephropathy is an important problem in patients with diabetes. However, little is known about the effect of dietary protein intake on albuminuria in patients with diabetes. Thus, the aim of this study was to clarify the association between dietary protein intake and change in urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.

Methods: In this retrospective cohort study, we included 143 patients (71 men, average 64.0 (10.5) years, and median 14.5 (6.7-38.5) mg/gCr) without macroalbuminuria (UAE over 300 mg/gCr). Change in UAE or eGFR was defined as increase of UAE or GFR/follow-up duration (year). Habitual protein intake was estimated by a self-administered diet history questionnaire.

Results: Median follow-up duration was 5 years. Logistic regression analyses showed that baseline UAE was associated with change in UAE (β = 0.217, p = 0.012), but the protein intake was not (β = -0.064, p = 0.454) (Table). In addition, baseline Cr was associated with change in eGFR (β = 0.344, p = 0.001), but the protein intake was not (β = 0.001, p = 0.988).

Conclusions: Dietary protein intake was not associated with change in UAE or eGFR. This result suggests that protein restriction is not necessary in patients without macroalbuminuria.

Multiple regression analysis on δUAE or δeGFR

δUAE standardized regression coefficient p value δeGFR standardized regression coefficient p value 
Log (UAE+1) 0.217 0.012 Log (UAE+1) 0.049 0.560 
Protein intake (g/kg/day) -0.064 0.454 Protein intake (g/kg/day) -0.033 0.698 
Usage of RAS inhibitor 0.114 0.193 Usage of RAS inhibitor -0.202 0.021 
Creatinine 0.047 0.646 Creatinine 0.398 <0.001 
Age -0.003 0.977 Age 0.061 0.490 
BMI 0.119 0.184 BMI -0.042 0.634 
Men -0.143 0.163 Men 0.121 0.237 
δUAE standardized regression coefficient p value δeGFR standardized regression coefficient p value 
Log (UAE+1) 0.217 0.012 Log (UAE+1) 0.049 0.560 
Protein intake (g/kg/day) -0.064 0.454 Protein intake (g/kg/day) -0.033 0.698 
Usage of RAS inhibitor 0.114 0.193 Usage of RAS inhibitor -0.202 0.021 
Creatinine 0.047 0.646 Creatinine 0.398 <0.001 
Age -0.003 0.977 Age 0.061 0.490 
BMI 0.119 0.184 BMI -0.042 0.634 
Men -0.143 0.163 Men 0.121 0.237 
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Disclosure

A. Kaji: None. Y. Hashimoto: Research Support; Self; Asahi Kasei Corporation, Fuji Foundation for Protein Research, Japan Society for the Promotion of Science, MSD K.K.. R. Sakai: None. T. Okamura: None. M. Yamazaki: None. M. Fukui: Research Support; Self; Grant-in-Aid for Scientific Research (C), Ono Pharmaceutical Co., Ltd., AstraZeneca, Astellas Pharma US, Inc., Daiichi Sankyo Company, Limited, Eli Lilly and Company, Kyowa Hakko Kirin Co., Ltd., Kissei Pharmaceutical Co., Ltd., MSD K.K., Novo Nordisk Foundation.

© 2018 by the American Diabetes Association.
2018
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