Nonalcoholic Fatty Liver Disease Is Associated With Increased Carotid Intima-Media Thickness Only in Type 2 Diabetic Subjects With Insulin Resistance

Context: The association between nonalcoholic fatty liver disease (NAFLD) and subclinical atherosclerosis in type 2 diabetes is controversial. Objective: The objective of the study was to investigate the participation of insulin resistance in the association of NAFLD and the carotid atherosclerotic burden in a large cohort of patients with type 2 diabetes. Design, Setting, and Patients: This was an observational study performed in 4437 consecutively enrolled patients with type 2 diabetes. Main Outcomes Measures: Hepatic steatosis and mean carotid intima-media thickness (C-IMT) were measured using ultrasonography. Insulin resistance was assessed using the short insulin tolerance test. Results: The prevalence of NAFLD was 72.7% in the whole study population. Among subjects with NAFLD, 23.2% were not insulin resistant. There were significant differences in C-IMT and the frequency of carotid atherosclerosis between groups classified by insulin resistance within the same NAFLD strata. C-IMT was highest in subjects with both NAFLD and insulin resistance [0.844 +/- 0.004 (mean +/- SE) mm vs 0.786 +/- 0.008, 0.821 +/- 0.007, and 0.807 +/- 0.006 mm, P for trend < .001, respectively, in insulin sensitive subjects without NAFLD, insulin resistant subjects without NAFLD, and insulin sensitive subjects with NAFLD]. These differences remained after adjusting for potential confounders. However, C-IMT in subjects having only NAFLD or insulin resistance was not higher than that in those with neither NAFLD nor insulin resistance. Conclusions: NAFLD is very common in subjects with type 2 diabetes, but NAFLD not accompanied by insulin resistance is not associated with a carotid atherosclerotic burden. However, having both NAFLD and insulin resistance seemed to be an independent predictor of increased C-IMT.