Plasma xanthine oxidase activity tied to insulin resistance, liver dysfunction in T2DM with MetS
Higher activity of plasma xanthine oxidase (XO) appears to be linked to insulin resistance and liver dysfunction among type 2 diabetes mellitus (T2DM) patients with metabolic syndrome (MetS), according to a recent Japan study.
Using highly sensitive fluorometric assays, researchers measured the plasma XO activity in 50 T2DM patients with MetS (mean age 55±14 years; 26 males). XO activity was signalled by the conversion of pterin to isoxanthopterin and was natural logarithm-transformed (ln) for subsequent statistical analyses.
Ln-XO activity was significantly and linearly correlated with fasting serum levels of immunoreactive insulin (r=0.52; p<0.001) and the homeostasis model assessment insulin resistance (HOMA-IR; r=0.51; p<0.001). There was also a weak but significant correlation with body mass index (r=0.39; p=0.01).
Indices of liver dysfunction also showed significant associations with ln-XO activity: ln-aspartate aminotransferase (r=0.79; p<0.001), ln-alanine aminotransferase (ALT; r=0.85; p<0.001) and ln-γ-glutamyltransferase (r=0.46; p<0.001).
In contrast, ln-XO activity was not correlated with ln-adiponectin (r=0.12; p=0.42), ln-high-sensitivity C-reactive protein (r=0.14; p=0.33) and serum uric acid (r=0.23; p=0.11).
Multiple regression analyses were performed to identify independent risk factors affecting plasma XO activity. The corresponding fully adjusted models showed that ln-ALT (r2=0.628; p=0.001) and HOMA-IR (r2=0.469; p=0.002) were significantly associated with plasma XO activity.
Moreover, “Plasma XO activity shows no apparent diurnal variations and no significant changes after meals or mild aerobic exercise,” said researchers.
“Through assessing plasma XO activities precisely in clinics, patients demonstrating normal level of serum uric acid with higher activity of XO can be screened, thereby possibly providing a clue to uncover hidden risks for T2DM and MetS,” they added.