The Dynamics of Carnitine, γ-butyrobetaine and Trimethylamine N-oxide in Diabetics and the Effects of Changes in Renal Function

Objectives: In diabetic kidney disease, vascular disorders progress alongside loss of renal function, possibly due to higher blood concentrations of angiopathic substances, such as gamma-butyrobetaine (γBB), produced by gut microbiota that feed on carnitine in dietary red meat. Therefore, we established the hypothesis that urinary γBB excretion declines with decreasing renal function, causing a rise in blood γBB concentration, leading to aggravated vascular injury. Methods: Our subjects were non-diabetics with normal renal function (N group) and diabetics with reduced renal function (D group). We measured blood concentration and urinary γBB excretion to compare the groups. We also compared blood γBB levels and urinary γBB excretions in diabetics with diabetic kidney disease (eGFR 30 mL/min/m2, NDKD group). Results: Blood γBB concentration in the D group was approximately 134.3% compared with the N group. It correlated negatively with eGFR (r = –0.85, p