To Örebro University

Background and aims: Individuals with metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (MASH) have higher prevalence of type 2 diabetes (T2D) and impaired fasting glycemia. Given the role of the liver as main contributor to endogenous glucose production (EGP), we investigated if hepatic glucose fluxes were increased with worsening of liver histology, from liver steatosis (SL) to MASH with advanced fibrosis, and the interplay with adipose tissue lipolysis.

Materials and methods: The cohort comprised n=260 subjects with liver biopsy from the EPoS cohort (92/168 Female/Male; 153/109 noT2D/T2D; 58/202 SL/MASH), of whom n=206 had transcriptomics of liver biopsy (EPoS-RNA) and n=68 (EPoS-flux) had measurement of fasting EGP and adipose tissue lipolysis by stable-isotope (6,6- 2 H 2 -glucose and U- 2 H 5 -glycerol infusion.). Intra-hepatic glucose fluxes were estimated using genome-scale metabolic modeling (GSMM) of transcriptomic data and results were validated vs tracer measurements.

Results: Tracer-measured EGP and hepatic insulin resistance were increased with histological severity (mainly with fibrosis and inflammation, Kruskal-Wallis’ test p< 0.05) and correlated with insulin resistance and tracer-measured adipose tissue lipolytic flux (Pearson’s test p<0.0001), even in absence of T2D. GSMM-analysis showed that high EGP was due to increased gluconeogenesis and anaplerosis and was associated with excess substrates uptake, rather than changes in the expression of glucogenic genes. However, hepatic expression of genes involved in insulin signaling (IRS1, IRS2, and AKT2) was reduced with the worsening of liver fibrosis and the presence of T2D (Kruskal-Wallis’ test p< 0.05).

Conclusion: In MASLD, not only lipids but also glucose metabolism is impaired. The dysregulation of EGP is due to the elevated release of gluconeogenic substrates from peripheral tissues and to the impairment in insulin signaling, and is associated with the severity of hepatic fibrosis and inflammation, rather than steatosis. These findings contribute to improve our understanding of the mechanisms underlying the increased risk of hyperglycemia and T2D in subjects with MASH.