Non-alcoholic fatty liver disease and insulin resistance: importance of risk factors and histological spectrum.

BACKGROUND Non-alcoholic fatty liver disease (NAFLD) has been associated with several metabolic conditions (MC) and secondary causes, but the relationship between insulin resistance (IR) and the underlying aetiology of NAFLD has not been extensively explored. OBJECTIVE To determine the frequency of IR among NAFLD patients and to describe IR according to risk factors and histological findings of the disease. METHODOLOGY A case-series study of 64 patients with clinical and histological diagnosis of NAFLD. IR was calculated by homeostasis model assessment (HOMA) and IR was considered when HOMA > or = 3. Histological grades of NAFLD were: stage 1, steatosis isolated; stage 2, steatosis and inflammation; stage 3, steatosis and ballooning degeneration; stage 4, steatosis and fibrosis and/or Mallory bodies. Fibrosis was graded 0-4 (cirrhosis). RESULTS IR was found in 21 (33%) patients. Among those with IR, 16 patients (76%) had associated MC and five patients (24%) had exposure to petrochemicals. The mean value of HOMA varied from 3.5 in NAFLD associated with MC to 1.6 in patients with exposure to petrochemicals (P < 0.03). Waist circumference was the metabolic factor most strongly associated with IR (P < 0.005). Steatohepatitis (NASH) was observed in 54 (84.3%) cases. The HOMA mean value was significantly higher in patients with advanced fibrosis. CONCLUSIONS IR occurred in 33% of the NAFLD patients, being more frequent among those with MC than among those with exposure to petrochemicals. The presence of IR in cases with advanced fibrosis suggests that it may influence the prognosis of NAFLD.