To our knowledge, this study is the first to identify dietary patterns associated with CKD in elderly patients with type 2 diabetes in China. Four distinct dietary patterns were identified, collectively explaining 45.8% of the dietary variance in the study population and reflecting the predominant dietary habits of elderly individuals in the Xiangcheng District, Suzhou. After adjustment for potential confounders, adherence to a balanced dietary pattern, characterized by elevated loadings of fruits, dairy products, eggs, snacks, crab, shellfish, fish, and shrimp, was significantly associated with reduced odds of CKD. In contrast, an imbalanced dietary pattern was associated with increased odds of CKD. No significant associations were observed between CKD and adherence to either the “traditional southern dietary pattern” or the “high-protein dietary pattern”.

Most prior population-based studies on diet and CKD have concentrated on individual dietary components or nutrients [25]. However, dietary intakes are complex and involve intricate nutrient interactions, which are not captured by single-component analyses. By identifying dietary patterns, we account for the synergistic effects of multiple nutrients as well as cultural and lifestyle factors, enabling a more comprehensive understanding of dietary influences on CKD. This method also enhances the relevance of findings for clinical practice and public health initiatives, as dietary patterns are more pragmatic targets for dietary guidelines [29]. Although there is growing advocacy for adherence to healthy dietary patterns globally, most of the currently recommended patterns are Western-oriented and may not adequately align with the dietary habits or cultural preferences of Chinese individuals, especially elderly populations. Tailored dietary recommendations are therefore essential to address nutritional disparities and optimize health outcomes in specific populations.

Previous studies have reported that adherence to established healthy dietary patterns, such as the Dietary Approaches to Stop Hypertension (DASH) diet or the Mediterranean diet, is associated with a reduced risk of CKD [30, 31]. The DASH diet emphasizes high consumption of fruits, vegetables, and low-fat or skim dairy products, while limiting saturated fats, cholesterol, and sugary items [32]. Similarly, the Mediterranean diet is characterized by high intake of vegetables, fruits, whole grains, legumes, nuts, and olive oil, alongside low consumption of red and processed meat [33]. Several components of the "balanced dietary pattern" identified in our study overlap with these widely recognized dietary models, but it also incorporates unique regional characteristics that align with the cultural and dietary habits of elderly patients with type 2 diabetes in the Xiangcheng District of Suzhou. These regional differences emphasize the influence of the unique geographical and cultural environment on dietary practices and the importance of tailoring dietary recommendations to specific populations.

Healthy dietary patterns have consistently been linked to a reduced incidence of CKD, largely through mechanisms involving dietary fiber and antioxidants [16, 34, 35]. Diets rich in fruits and vegetables provide essential antioxidants, such as vitamins C and E and carotenoids, which reduce oxidative stress and systemic inflammation—both major contributors to CKD progression [10, 17]. Additionally, a diet high in fruits and low in animal protein reduces the endogenous acid load, alleviating nephron stress and supporting long-term kidney health [36]. Evidence from a large cross-sectional study of 56,476 individuals with metabolic syndrome in China demonstrated that adherence to dietary patterns rich in vegetables, fruits, and grains, as well as milk and dairy, was associated with reduced levels of blood urea nitrogen, creatinine, and uric acid and improved eGFR [37]. Dietary fiber, a key component of plant-based foods including vegetables, fruits, whole grains, nuts, legumes, and seeds, plays a significant role in mitigating CKD risk [38, 39]. Sufficient fiber intake confers a range of health benefits, such as promoting gut microbiota diversity, strengthening the intestinal barrier, reducing systemic inflammation, and improving bowel function. Importantly, adequate fiber intake has been associated with decreased production of uremic toxins, which are implicated in CKD progression and increased mortality [38, 40].

The meat-seafood-egg dietary pattern, characterized by a high intake of protein and saturated fat, is not recommended for individuals with mild kidney insufficiency, as elevated consumption of meat, fish, eggs, and other non-dairy protein sources may accelerate CKD progression [41]. Experimental studies have demonstrated that a low-protein diet can mitigate renal damage by inhibiting endogenous uric acid synthesis and improving renal tubular injury, as compared to a standard protein diet (18% protein), in streptozotocin-induced diabetic rats [42]. In our study, the high-protein dietary pattern was not significantly associated with CKD, while the balanced dietary pattern exhibited a lower factor loading for aquatic protein sources such as freshwater fish, shrimp, crab, and shellfish, with values around 0.2. This indicates that protein intake in the balanced dietary pattern is relatively lower compared to the high-protein dietary pattern, possibly contributing to the protective effect observed.

Interestingly, our finding that snacks, as a component of the balanced dietary pattern, were associated with a lower prevalence of CKD among elderly patients with type 2 diabetes was counterintuitive. Previous evidence suggests that snacks—particularly those representative of Western dietary patterns—are often high in energy, carbohydrates, fats, and sodium, while being low in potassium and calcium, all of which are linked to an increased risk of metabolic syndrome, gout, and other chronic diseases [43,44,45,46]. However, other studies have indicated that snacking can also be associated with higher dietary quality and greater intake of key nutrients such as vitamins, potassium, and magnesium [47, 48]. The heterogeneity of snack composition makes it essential to account for nutritional content when assessing their health effects. Properly selected snacks do not inherently degrade diet quality; rather, they can increase opportunities for healthy, low-energy food choices and contribute positively to dietary diversity. Additionally, balanced snacking can significantly enhance daily micronutrient and macronutrient intake [49].

The snacks consumed in our study population in the Xiangcheng District, Suzhou, exemplify traditional "Su Cuisine" and are characterized by their fragrance, sweetness, fine texture, loose consistency, and ingredients like glutinous rice—hallmarks of local dietary habits. Located adjacent to Yangcheng Lake, a major freshwater lake in Jiangsu Province and one of the most significant fishing areas in China, the Xiangcheng District benefits from abundant biological resources [50]. Yangcheng Lake provides a diverse array of aquatic species, traditionally referred to as the "Six Treasures of Yangcheng Lake," including species such as salmon, turtles, whitefish, eels, shrimp, and crabs. Among these, the Chinese mitten crab, often referred to as the "King of Crabs," is renowned for its exceptional taste, unique aroma, and high nutritional value. It is a rich source of minerals such as zinc, iron, copper, and phosphorus and provides high-quality protein [51]. These foods align with the local cultural and geographical context while offering considerable dietary and nutritional value, which may contribute to the unique dietary patterns observed in this study.

In our study, adherence to the "imbalanced dietary pattern" was positively associated with a higher risk of CKD. This pattern was characterized by a prominent consumption of green leafy vegetables, refined grains, and red meat, along with low intake of legumes and seafood, and an overall lack of diversity in other dietary components. These findings are partially consistent with previous studies, which have demonstrated a positive association between high red meat consumption and the risk of CKD. For instance, the Atherosclerosis Risk in Communities (ARIC) study, which followed 12,000 participants over a median of 23 years, reported that 2,632 individuals developed CKD, with red and processed meat intake being significantly associated with an increased risk of CKD (HR = 1.19, 95% CI: 1.03–1.36) [52]. Recent research has pointed to trimethylamine N-oxide (TMAO)—a metabolite generated by gut microbial metabolism of dietary red meat—as a potential mediator of the adverse effects of red meat consumption on cardiovascular and kidney health [53].

In this study, we investigated the association between diet and CKD among elderly patients with type 2 diabetes in China. The strengths of our study include its large sample size, population-based design, and the availability of detailed epidemiological and clinical data, which allowed for extensive adjustment for potential confounders. Unlike previous studies, we focused on a specific population of elderly diabetic patients with CKD, who may differ from populations studied in other dietary guidelines. This population-specific focus provides new insights into dietary management tailored for elderly Chinese diabetic patients with CKD. Importantly, we identified dietary patterns that not only align with the cultural and regional dietary habits in China but may also serve as healthy, practical options for this high-risk group. These findings provide valuable, real-world evidence to inform dietary recommendations aimed at improving the renal health of elderly Chinese diabetic patients.

This study has several limitations that should be acknowledged. First, the focus on elderly patients with type 2 diabetes in a specific region may restrict the generalizability of the findings to other populations; however, this allowed us to identify dietary patterns particularly relevant to this demographic, providing valuable insights for targeted approaches. Second, the use of self-reported dietary data through food frequency questionnaires is subject to recall bias, and the identification of dietary patterns via factor analysis limits reproducibility. Additionally, while rigorous adjustments were made for potential confounders, residual confounding cannot be entirely excluded, particularly given the lack of detailed nutrient-level data (e.g., energy, protein, and fat intake). Lastly, the cross-sectional design precludes causal inference, highlighting the need for future longitudinal studies to confirm these associations.