Circulating betatrophin/ANGPTL8 levels correlate with body fat distribution in individuals with normal glucose tolerance but not those with glucose disorders

Abstract

Background: The relationship between betatrophin/ANGPTL8 and obesity has been investigated using body mass index (BMI); however, since BMI reflects overall adiposity rather than body fat distribution, it remains unclear whether fat deposition in different areas of the body affects betatrophin expression. Here, we investigated the correlation between circulating betatrophin levels and body fat distribution in patients with different glucose tolerance. Methods: In 128 participants with impaired glucose tolerance (IGT; n = 64) or normal glucose tolerance (NGT; n = 64), we measured circulating betatrophin levels by enzyme-linked immunosorbent assay and body fat distribution (subcutaneous, visceral, and limb fat) using magnetic resonance imaging (MRI) and a body fat meter. Results: After controlling for age, sex, and BMI, betatrophin was correlated positively with visceral adipose tissue-to-subcutaneous adipose tissue ratio ( VAT/SAT ratio; r = 0.339, p = 0.009) and negatively with body fat ratio (BFR; r = -0.275, p = 0.035), left lower limb fat ratio (LLR; r = -0.330, p = 0.011), and right lower limb fat ratio (RLR; r = -0.288, p = 0.027) in the NGT group, with these correlations remaining after controlling for triglycerides. VAT/SAT ratio (standardized β = 0.419, p = 0.001) was independently associated with serum betatrophin levels; however, betatrophin was not associated with body fat distribution variables in the IGT group. Conclusions: Circulating betatrophin levels correlated positively with VAT/SAT ratio and negatively with lower limb fat, but not subcutaneous or upper limb fat, in individuals with normal glucose tolerance. Thus, betatrophin may be a poten­tial biomarker for body fat distribution in individuals without glucose disorders.