Relation of gut microbiota-dependent metabolite trimethylamine-N-oxide with insulin resistance and cardiovascular risk indices in type 2 diabetic patients

Abstract

Background Gut microbiota dysbiosis in type 2 diabetes mellitus (T2DM) causes an increase in the metabolite, trimethylamine-N-oxide (TMAO) that contributes to increased cardiovascular disease risk and exacerbates hyperglycemia. Aim The aim of this study was to assess serum TMAO and its relation with insulin resistance (IR) and cardiovascular risk indices in type 2 diabetic patients. Patients and methods This case–control study was conducted on 60 type 2 diabetic patients and 28 healthy age- and sex-matched individuals. Patients were divided into two groups according to the presence of ischemic heart disease (IHD). Fasting and 2-h postprandial blood glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, glycosylated hemoglobin, fasting serum insulin, and serum TMAO were measured. Assessment of IR index by using Homeostatic Model Assessment HOMA-IR was done. Neck ultrasound was done to assess carotid intima-media thickness (CIMT). Results All diabetic patients had significantly elevated TMAO values than controls. TMAO levels correlated positively with fasting serum insulin and HOMA-IR in IHD-diabetic patients, and correlated negatively with CIMT in diabetic patients both with and without IHD. Conclusion Serum TMAO levels were significantly higher in type 2 diabetic patients than controls. TMAO showed a positive correlation with fasting insulin and HOMA-IR in the IHD-diabetic patients and a negative correlation with CIMT in diabetics both with and without IHD. Serum TMAO more than 7 ng\ml may be considered a potential diagnostic biomarker for T2DM with IHD in Egyptians with T2DM. HOMA-IR level of more than 1.25 can be used for the diagnosis of IR.