Renal function trajectories of Japanese adults with diabetic kidney disease on different diet therapies including energy-restricted and low-carbohydrate diets: a retrospective cohort study

Tomomi Shirai; Sakiko Inaba; Miyu Maemura; Maki Saho; Miyu Sato; Mariko Sanada; Yoko Tsukamoto; Gaku Inoue; Taichi Nagahisa; Shinichi Tanaka; Hajime Tanaka; Hideaki Kurata; Takeshi Katsuki; Toshihide Kawai; Satoru Yamada

doi:10.1007/s13340-025-00808-y

Renal function trajectories of Japanese adults with diabetic kidney disease on different diet therapies including energy-restricted and low-carbohydrate diets: a retrospective cohort study

Diabetol Int. 2025 Mar 21;16(3):493-503. doi: 10.1007/s13340-025-00808-y. eCollection 2025 Jul.

Authors

Affiliations

¹ Diabetes Center, Kitasato University Kitasato Institute Hospital, 5-9-1 Shirokane, Minato-Ku, Tokyo, 108-0072 Japan.
² Department of Food and Nutritional Science, Graduate School of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-Ku, Tokyo, 156-8502 Japan.
³ Faculty of Land and Food System, The University of British Columbia, 2329 West Mall, Vancouver, BC V6T 1Z4 Canada.
⁴ Department of Diabetes and Endocrinology, Tokyo Saiseikai Central Hospital, 1-4-17 Mita, Minato-Ku, Tokyo 108-0073 Japan.

Abstract

Objective: Recently, the Japan Diabetes Society changed its nutrition recommendations and now recognizes a low-carbohydrate diet as an effective dietary approach. There has been controversy regarding low-carbohydrate diets in relation to renal function. That is, high protein intake may lead to renal damage through hyperfiltration. Global nutritional therapy for diabetic kidney disease (DKD) recommends a protein intake of 0.8 g/kg body weight (BW)/day. In Japan, the recommended protein intake is precisely determined based on the chronic kidney disease stage. However, evidence supporting the positive health impact of such protein restriction is scarce. Therefore, we aimed to investigate the effect of a low-carbohydrate diet without protein restriction on the estimated glomerular filtration rate (eGFR) decline rate.

Methods: Clinical data of patients with DKD in Tokyo Saiseikai Central Hospital and Kitasato Institute Hospital in Japan were retrospectively analyzed between February 2019 and December 2023. Sixty-eight participants were classified into two groups based on their diet: the energy-restricted and low-carbohydrate groups.

Results: The protein intake of the low-carbohydrate group was significantly higher than that of the energy-restricted group (1.2 ± 0.4 and 1.0 ± 0.2 g/kg BW/day, respectively). No significant differences were observed in the baseline, endpoint, or slope of eGFR between the two groups.

Conclusions: This study suggests that among Japanese adults with DKD, the protein intake difference between energy-restricted and low-carbohydrate diets does not form any gap in eGFR decline rates.

Supplementary information: The online version contains supplementary material available at 10.1007/s13340-025-00808-y.

Keywords: CKD; DKD; Diabetes mellitus; Low-carbohydrate diet; Nutritional therapy; eGFR.

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