AIMS: This study aimed to identify the longitudinal associations between protein intake, and composite renal outcomes in people with type 2 diabetes. METHODS: To examine the association between baseline total, animal, and plant protein intake and the risk of developing a composite renal outcome in 3,109 Japanese people with type 2 diabetes who participated in a cohort study at a tertiary care hospital, we used a Cox proportional hazards model. RESULTS: During a median follow-up of 6.0 years, we observed 185 renal outcomes. Compared with the 1st quintile, the multivariable-adjusted HRs for outcome were 1.13 (p = 0.440), 1.04 (pp= 0.874), 1.40 (p = 0.215), and 2.16 (p = 0.002), respectively for the 2nd to 5th quintile of total protein intake, and 0.93 (p = 0.681), 1.1 (p= 0.596), 1.1 (p = 0.607), and 2.02 (p <
0.002), respectively for the 2nd to 5th quintile of animal protein intake. However, a significant association of total plant intake was not observed. In the analysis evaluating the joint association between protein intake and composite renal outcome with baseline estimated glomerular filtration ratio (eGFR), total protein and animal protein intake were substantially associated with a higher risk of composite renal outcome when the baseline eGFR was below approximately 60 mL/min/1.73 CONCLUSIONS: Baseline total protein intake is associated with a higher risk of developing a composite renal outcome during follow-up in people with type 2 diabetes and low baseline eGFR, and this association may be elucidated by a higher animal protein intake. Plant protein was not associated with renal outcome.