Type 2 diabetes is frequently complicated by nonalcoholic fatty liver disease (NAFLD) , which is mainly caused by high-fat and high-calorie diets, and obesity. In this regard, both the quantity and quality of fat accumulating in the liver are important, and in particular, the proportion of each fatty acid may be an important biomarker for NAFLD. We investigated whether serum fatty acid composition, especially n-6 polyunsaturated fatty acid (PUFA) and, saturated fatty acid (MUFA) and desaturase activity are associated with NAFLD in type 2 diabetes patients. Eighty-five type 2 diabetes patients (age: 60.3±13.9 years, BMI 27.5±5.8 kg/m2) who had no history of alcohol drinking, and had a negative result for hepatitis viruses were included as study subjects. Fatty liver (FL) was diagnosed based on liver ultrasonographic findings. Patients with FL were included in the FL group (n=51) , whereas those without FL included in the non-FL group (n=34) . Serum fatty acid levels were measured using gas chromatography. Desaturase activity for n-6 PUFAs was calculated as the ratio of arachidonic acid to dihomo-gamma-linolenic acid (DGLA) for Δ5 desaturase (D5D) . Waist circumference, BMI, serum triglyceride (TG) concentration, and ALT level were significantly higher in the FL group than in the non-FL group. The FL group also demonstrated higher levels of palmitic acid (PAL) and stearic acid (STA) , PAL/STA ratio, and DGLA than the non-FL group. In the FL group D5D activity was significantly lower than that in the non-FL group. PAL level, DGLA, and PAL/STA ratio showed a significant positive correlation with TG and ALT levels. Multiple regression analysis showed that DGLA was independently associated with FL development. These results suggest that type 2 diabetes patients with NAFLD have changes in their blood fatty acid profile, especially increased DGLA and PAL levels. The high levels of blood DGLA indicate downregulation of n-6 PUFA metabolism, probably caused by the decreased activity of D5D.
M.Higa: None. T.Ichijo: None.