Malnutrition is a critical issue among older inpatients, yet limited large-scale research related to this issue has been conducted in China. This study aimed to examine the nutritional status and support of older inpatients in China, assess the associations between disease categories and malnutrition on admission, and explore effective nutritional intervention.

A total of 24,139 older participants from the China Nutrition Fundamental Data 2020 Project were included. Malnutrition was measured by the Global Leadership Initiative on Malnutrition criteria. Adjusted odds ratios (aORs) were calculated using logistic analysis.

The overall frequency of malnutrition on admission was 18.9%. Participants with infections were more likely to have malnutrition (aOR = 1.929, 95% CI 1.486–2.504). Risks that were also noted for malnutrition included neoplasms (aOR = 1.822, 95% CI 1.697–1.957), hemic and lymphatic diseases (aOR = 1.671, 95% CI 1.361–2.051), nervous system diseases (aOR = 1.222, 95% CI 1.126–1.326), respiratory diseases (aOR = 1.613, 95% CI 1.490–1.746), and digestive system diseases (aOR = 1.462, 95% CI 1.357–1.577). Further, 32.26% inpatients with malnutrition during hospitalization didn’t receive nutritional support. Oral nutrition supplements, enteral tube feeding, and parenteral nutrition were associated with stable or improved nutritional status.

Older inpatients were at a high risk for malnutrition but did not receive adequate nutritional intervention. More resources and attention need to be devoted to the nutritional status of older inpatients and targeted nutritional support.