Nutritional management is crucial in patients with chronic kidney disease. Therefore, it is important to assess nutritional status and detect malnutrition, especially in patients with diabetes. However, there is currently a lack of evidence regarding the relationship between nutritional indices and renal function in patients with type 2 diabetes. This study investigated whether the geriatric nutritional risk index (GNRI) is related to renal prognosis in type 2 diabetes patients. The study included 946 type 2 diabetes patients enrolled in the Fukushima Cohort Study. The primary endpoint of this study was a renal event, defined as a combination of a 50% decline in eGFR from baseline and end-stage kidney disease. All-cause death and new cardiovascular events were also measured as secondary outcomes. The association between GNRI and these endpoints was assessed using Cox regression analysis. The median patient age was 66 years, 57% were men, the median eGFR was 67.9 mL/min/1.73 m2, and the median GNRI was 100.0. Compared to patients in the highest GNRI tertile, patients in the lowest tertile had a significantly increased risk of therenal event (HR 5.15, 95% CI 2.51-10.6) and all-cause death (HR 2.30, 95% CI 1.20-4.42). A significant association was not observed between GNRI levels and cardiovascular events. We observed an association between poor nutritional status, assessed by GNRI, and adverse outcomes in patients with type 2 diabetes. Nutritional status assessment has potential utility as a prognostic tool for individuals with type 2 diabetes.