Nonalcoholic steatohepatitis, insulin resistance, and metabolic syndrome: Further evidence for an etiologic association

TLDR

The derangement of insulin regulation, often linked to metabolic syndrome, may causally contribute to NASH development. This study aimed to assess the prevalence of metabolic‑syndrome components in primary NASH and to determine whether liver disease drives peripheral hyperinsulinemia. Nineteen NASH patients and nineteen matched controls were enrolled, and plasma glucose, insulin, and C‑peptide were measured during oral and intravenous glucose tolerance tests, with insulin sensitivity and secretion quantified by minimal‑model analysis. NASH patients exhibited markedly reduced insulin sensitivity and increased insulin secretion compared with controls, with similar hepatic insulin extraction; nearly half met metabolic‑syndrome criteria, indicating that hyperinsulinemia and insulin resistance in NASH arise from compensatory pancreatic secretion rather than impaired hepatic extraction.

Abstract

This study aims to determine the presence of the components of the metabolic syndrome in primary nonalcoholic steatohepatitis (NASH) and to assess the role of liver disease in the genesis of peripheral hyperinsulinemia. Nineteen patients (18 men and 1 woman; mean age, +/- SD, 38 +/- 10 years; body mass index [BMI], 26 +/- 2 kg/m(2)) with histologic evidence of NASH were enrolled; 19 age- and sex-matched normal subjects were investigated as controls. Plasma glucose, insulin, and C-peptide levels were measured during an oral glucose tolerance test, and a frequently sampled intravenous glucose tolerance test (FSIGT), analyzed by minimal modeling technique, was performed. Compared with controls, the NASH group had lower insulin sensitivity (3.84 +/- 2.44 vs. 7.48 +/- 3.01 10(-4) x min(-1)/microU/mL; P =.0003) and higher total insulin secretion (21 +/- 13 vs. 10 +/- 3 nmol/L in 240 minutes; P =.001). Hepatic insulin extraction was similar in both groups (69.8% +/- 16.1% vs. 70.2% +/- 18.3%; P =.854). According to the results of the oral glucose tolerance test, no patient was classified as diabetic, 5 were classified as glucose intolerant, and 1 was classified as having impaired fasting glycemia. Nine patients (47%) had at least the 2 minimum criteria required to define the metabolic syndrome according to the European Group for the Study of Insulin Resistance (EGIR). In conclusion, hyperinsulinemia and insulin resistance occur frequently in patients with NASH; these conditions do not stem from a reduced hepatic insulin extraction but from an enhanced pancreatic insulin secretion compensatory to reduced insulin sensitivity. The derangement of insulin regulation, often associated with the metabolic syndrome, may play a causal role in the pathogenesis of NASH.