Serum Amyloid A, Malnutrition, Relative Hyperglycemia, and the Development of Diabetic Kidney Disease in Type 2 Diabetes

BACKGROUND: Serum amyloid A (SAA) plays a vital role in the acute-phase response, acting as a cytokine-like protein. Few studies have examined the role of SAA, malnutrition, and the stress hyperglycemia ratio (SHR) in the development of diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM). This study investigated the relationship between SAA, nutritional indices, SHR, inflammatory biomarkers, and the prevalence of DKD in overweight and non-overweight patients with T2DM. METHODS: A total of 245 patients with newly diagnosed T2DM were evaluated. Levels of SAA, C-reactive protein (CRP), hemoglobin A1c (HbA1c), and fasting plasma glucose (FPG) were measured. SHR, controlling nutritional status (CONUT) score, prognostic nutritional index (PNI), systemic inflammatory index (SII), and inflammatory burden index (IBI) were calculated. CONUT scores ≥ 5.0 and 0 - 1 were defined as high and normal CONUT scores, indicating malnutrition and normal nutritional status, respectively. RESULTS: Patients with a high CONUT score had a 2.9-fold higher prevalence of DKD than those with a normal CONUT score. The prevalence of DKD was significantly higher in patients with elevated SAA levels than in those without elevated SAA levels, whereas no significant difference was observed between patients with elevated and non-elevated CRP levels. PNI and CONUT score were more closely correlated with SAA and CRP levels in non-overweight patients with diabetes than in overweight patients with diabetes. Levels of SAA, CONUT score, SII, and IBI were significantly higher in non-overweight patients than in overweight patients. SHR was more strongly associated with DKD prevalence (odds ratio: 2.471; 95% confidence interval, 1.164 - 5.746; p < 0.001) than either HbA1c or FPG. Inflammation combined with malnutrition significantly increased the risk of DKD compared with inflammation or malnutrition alone. CONCLUSIONS: Low nutritional status plays a crucial role in the development of DKD, possibly in connection with systemic inflammation, particularly in non-overweight patients with T2DM. SAA and SHR are more closely associated with DKD risk than CRP and HbA1c in patients with diabetes.