Relationship between serum trimethylamine N-oxide (TMAO) and asprosin and diabetic nephropathy in patients with type 2 diabetes

Diabetes mellitus, particularly type 2 diabetes, is a major global public health concern due to its increasing prevalence and associated complications. Diabetic nephropathy—a microvascular complication observed in approximately 40% of type 2 diabetic patients—is one of the leading causes of chronic kidney disease. This study aimed to investigate the relationship between serum TMAO and asprosin levels and the presence of diabetic nephropathy in patients diagnosed with type 2 diabetes. The study population comprised individuals aged 30 to 75 years, including 60 type 2 diabetic patients (divided equally into groups with and without diabetic nephropathy) and 30 healthy controls matched for age and gender. Patient data were obtained through a retrospective review of files from the Fırat University Faculty of Medicine, Department of Internal Medicine Polyclinic and Clinic. Diabetic nephropathy was defined based on the presence of positive proteinuria in complete urine analysis and/or a serum creatinine level exceeding 1.2 mg/dL. TMAO is a biologically active metabolite produced by the oxidation of trimethylamine, which is synthesized by gut microbiota and converted in the liver by the enzyme flavin-containing monooxygenase 3 (FMO3). Asprosin is a protein hormone predominantly secreted by white adipose tissue that stimulates hepatic glucose production during fasting. Both biomarkers have been implicated in the pathophysiology of diabetes and its chronic complications. Serum TMAO and asprosin levels were measured using commercial ELISA kits, and the data were statistically analyzed using IBM SPSS 27.0. The results revealed that patients with diabetic nephropathy exhibited significantly higher serum TMAO and asprosin levels compared to type 2 diabetic patients without nephropathy and healthy controls (TMAO: p=0.001; asprosin: p=0.002). Furthermore, significant correlations were observed between these biomarker levels and renal function parameters, such as glomerular filtration rate (GFR), as well as metabolic parameters including fasting plasma glucose. These findings suggest that serum TMAO and asprosin could serve as potential biomarkers for the early diagnosis, risk stratification, and monitoring of diabetic nephropathy in patients with type 2 diabetes. The study's results may contribute to the development of more effective strategies for the prevention and management of diabetic nephropathy.