The role of trimethylamine-N-oxide level in the diagnosis of diabetic retinopathy and the differential diagnosis of diabetic and nondiabetic retinopathy

ABSTRACT Purpose: Trimethylamine N-oxide serum levels have been associated with type 2 diabetes mellitus and its complications. The current study aimed to find out if plasma trimethylamine N-oxide level may be a novel marker in the diagnosis of diabetic retinopathy and if it can be used in the differential diagnosis of diabetic and nondiabetic retinopathy. Methods: The study included 30 patients with diabetic retinopathy, 30 patients with nondiabetic retinopathy, 30 patients with type 2 diabetes mellitus without retinopathy, and 30 healthy control participants. Biochemical parameters, serum IL-6, TNF-α, and trimethylamine N-oxide levels were measured in all participants. Results: Trimethylamine N-oxide level was significantly higher in diabetic retinopathy than in the other groups (p<0.001). There was no significant difference in trimethylamine N-oxide levels between nondiabetic retinopathy and control or type 2 diabetes mellitus Groups. There was a significant positive correlation between trimethylamine N-oxide level and elevated FPG, BMI, HOMA-IR score, BUN, IL-6, and TNF-α levels. Conclusion: The current study showed that the trimethylamine N-oxide level is elevated in diabetic retinopathy. These findings suggest that serum trimethylamine N-oxide level might be a novel marker for diabetic retinopathy, and it might be used in the differential diagnosis of diabetic and nondiabetic retinopathy.

摘要
研究目的：血清氧化三甲胺（trimethylamine N-oxide, TMAO）水平与2型糖尿病及其并发症密切相关。本研究旨在探讨血浆氧化三甲胺水平是否可作为糖尿病视网膜病变的新型诊断标志物，以及能否用于糖尿病性与非糖尿病性视网膜病变的鉴别诊断。

研究方法：本研究共纳入4组受试者，包括糖尿病视网膜病变患者30例、非糖尿病性视网膜病变患者30例、无视网膜病变的2型糖尿病患者30例，以及健康对照受试者30例。对所有受试者的生化指标、血清白细胞介素-6（interleukin-6, IL-6）、肿瘤坏死因子-α（tumor necrosis factor-α, TNF-α）及氧化三甲胺水平进行检测。

研究结果：糖尿病视网膜病变组的氧化三甲胺水平显著高于其余三组（p<0.001）。非糖尿病性视网膜病变组与健康对照组、2型糖尿病无视网膜病变组的氧化三甲胺水平无显著差异。氧化三甲胺水平与空腹血糖（fasting plasma glucose, FPG）、体重指数（body mass index, BMI）、胰岛素抵抗稳态模型评估（homeostasis model assessment of insulin resistance, HOMA-IR）评分、血尿素氮（blood urea nitrogen, BUN）、IL-6及TNF-α水平呈显著正相关。

研究结论：本研究结果显示，糖尿病视网膜病变患者的血清氧化三甲胺水平升高。上述发现提示，血清氧化三甲胺水平或可成为糖尿病视网膜病变的新型诊断标志物，且可用于糖尿病性与非糖尿病性视网膜病变的鉴别诊断。