Association of cardiorespiratory fitness with elevated hepatic enzyme and liver fat in Japanese patients with impaired glucose tolerance and type 2 diabetes mellitus

Abstract

No study has so far determined whether a favorable level of cardiorespiratory fitness (CF) contributes to a reduced risk of elevated hepatic enzymes and a high degree of liver fat in patients having various metabolic risks. This study investigated the association between the maximal oxygen uptake (VO2 max) and the prevalence of elevated liver enzymes and high liver fat, while considering such factors as abdominal obesity, hyperinsulinemia and the other metabolic risks. The study enrolled newly diagnosed Japanese patients (n = 84; 52 males and 32 females; aged 25-69 years) with impaired glucose tolerance (IGT) and type 2 diabetes mellitus (Type2DM) who did not receive any intervention or pharmacological therapy. The subjects were divided into 3 groups according to the distribution of the VO2max for each sex. The odds ratios (ORs) for the prevalence of elevated aspartate and alanine aminotransferase (AST and ALT) and high degree of liver fat adjusted for age, sex, disease type, daily ethanol intake, and current smoking were significantly lower in the moderate- and high CF groups in comparison to the low CF group. In addition, a significant OR for AST was maintained in the moderate and high CF group after adjusting for abdominal obesity and/or hyperinsulinemia. The significant ORs for the prevalence of elevated ALT and a high degree of liver fat were attenuated after adjusting for abdominal obesity and/or hyperinsulinemia. No significant OR for the prevalence of elevated gamma-glutamyl transferase (GGT) was recognized in all logistic models. These results indicated that CF was negatively and independently associated with the prevalence of elevated AST even in Japanese diabetic patients having various metabolic risks. It was concluded that the AST level might be useful as a simple marker reflecting physical inactivity in such subjects. Key pointsThe prevalence of elevated AST was negatively, and strongly associated with the CF level independent of abdominal obesity, hyperinsulinemia, and the other confounders in the subjects with glucose intolerance.The association between the CF level and both an elevated ALT level and a high degree of liver fat, as defined by the L/S ratio of CT images depended on abdominal fat and/or hyperinsulinemia in the subjects with glucose intolerance.No association was recognized between CF and elevated GGT in the subjects with glucose intolerance in the subjects with glucose intolerance.Having a favorable level of CF could lead to a reduced risk of hepatic-related abnormalities even in diabetic patients having the other metabolic risks.

Keywords: Cardiorespiratory fitness; abdominal obesity; hepatic enzyme; insulin resistance; non-alcoholic fatty liver.