Non-alcoholic fatty liver disease is associated with carotid artery wall thickness in diet-controlled Type 2 diabetic patients

Non-alcoholic fatty liver disease (NAFLD) is closely associated with several metabolic syndrome (MetS) features. We assessed whether NAFLD is significantly associated with carotid artery intima-media thickness (IMT), as a marker of subclinical atherosclerosis, and whether such association is independent of classical cardiovascular risk factors and MetS features. We studied 100 diet-controlled Type 2 diabetic patients with ultrasonographically diagnosed NAFLD and 100 diabetic patients without NAFLD who were comparable for age and sex. Main outcome measures were carotid IMT (by ultrasonography), classical risk factors, insulin resistance [as estimated by homeostasis model assessment (HOMA)-IR] and MetS (as defined by the Adult Treatment Panel III criteria). NAFLD patients had a markedly greater carotid IMT (1.24 +/- 0.13 vs 0.95 +/- 0.11 mm; p<0.001) than those without the condition. The MetS and all its clinical traits were more highly prevalent in those with NAFLD (p<0.001). Adjustment for age, sex, smoking history, diabetes duration, glycosylated hemoglobin, LDL cholesterol, liver enzymes and microalbuminuria did not really affect the significant differences in carotid IMT that were observed between the groups. Further adjustment for the MetS also had little impact, but additional adjustment for HOMA-IR score consistently attenuated any statistical significance (p=0.28). In multivariate regression analysis, HOMA-IR score along with age and MetS (principally raised blood pressure values) were independently related to carotid IMT, whereas NAFLD was not. In conclusion, these results suggest that among diet-controlled Type 2 diabetic individuals the significant increase of carotid IMT in the presence of NAFLD is largely explained by HOMA-estimated insulin resistance.