Correlation between retinopathy and plasma trimethylamine-N-oxide level in patients with type 2 diabetes mellitus

  Objective  To explore the correlation between plasma trimethylamine-N-oxide(TMAO) level and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus(T2DM).

  Methods  A total of 102 patients with T2DM were selected and divided into non-diabetic retinopathy (NDR) group (n=38), non-proliferative DR(NPDR) group (n=35) and proliferative DR(PDR) group (n=29) according to presence of DR and its clinical diagnostic criteria for staging. Another 40 healthy persons with physical examinations were chosen as control group. Plasma TMAO concentration was determined by stable isotope dilution liquid chromatography tandem mass spectrometry(LC-MS/MS). The general data and laboratory indexes of the four groups were compared, and the correlation between plasma TMAO concentration and clinical parameters was analyzed. Multivariate Logistic regression analysis was used to screen the main risk factors of DR. Receiver operating curve (ROC) was used to analyze the efficacy of plasma TMAO concentration in the diagnosis of DR.

  Results  The duration of diabetes in the PDR group was significantly longer than that in the NDR group and NPDR group (P < 0.05). The levels of fasting blood glucose (FPG), glycosylated hemoglobin (HbA1c), C-reactive protein (CRP) and TMAO in four groups showed significant differences (P < 0.05). Spearman correlation analysis showed that TMAO was positively correlated with course of diabetes, higher levels of FPG, HbA1c and CRP (P < 0.05). Logistic regression analysis showed that long course of diabetes, and higher levels of FPG, HbA1c, CRP and TMAO were the main risk factors of DR (P < 0.05). ROC curve analysis showed that the area under curve (AUC) of DR diagnosed by TMAO alone was 0.833, was 0.802 by course of diabetes and detection of FPG, HbA1c and CRP in combination, and was 0.879 by course of diabetes and detection of FPG, HbA1c, TMAO and CRP.

  Conclusion  Elevated plasma TMAO level, one of the main risk factors of DR, is related to the occurrence and severity of DR in T2DM patients, and combination of course of diabetes, TMAO, FPG, HbA1c, CRP has a high accuracy in the diagnosis of DR.