Polyunsaturated fatty acid (PUFA) is an essential class of dietary fatty acids, because of the lack of endogenous enzymes for desaturation in humans. Previous research on n-3 PUFA has demonstrated several health benefits and antiatherogenic actions, but n-6 PUFA have not received much research attention. We investigated whether serum fatty acid composition, especially n-6 PUFAs and desaturase activity, is associated with obesity in type 2 diabetic patients. Subjects were 80 type 2 diabetic patients (age: 60.3±13.9 years) who had no EPA agent intake. They were divided into two groups: obese group (n=52) with a BMI more than 25 kg/m2 and non-obese group (n=28) with a BMI less than 25 kg/m2. Fatty acid levels in serum were measured using gas chromatography. The desaturase activity for n-6 PUFAs was calculated as the arachidonic acid/dihomo-gamma-linolenic acid (DGLA) ratio for Δ5 desaturase (D5D). The obese group revealed a higher saturated fatty acid (SFA) and DGLA levels than those in the non-obese group. No significant difference was observed in the serum n-3 PUFA levels between the two groups. The D5D index of the obese group was significantly lower than that of the non-obese group. Serum DGLA levels showed significant positive correlations with waist circumference, BMI, triglyceride, and hepatic AST and ALT levels. Moreover, SFA showed a significant positive correlation with BMI. The levels of D5D index showed a significant negative correlation with BMI. Increase in serum DGLA levels was related to the number of metabolic factors. These results suggest that type 2 diabetic patients with obesity had changes in their blood fatty acid profile, especially increased DGLA levels. The high levels of blood DGLA indicate downregulation of n-6 metabolism, probably caused by the decreased activity of D5D. The fat quality in the diet and changes in desaturase activity might contribute to the development of obesity.
M. Saito: None. M. Higa: None. T. Suzuki: None. M. Michishita: None. M. Hijikata: None. K. Yamashita: None. K. Ikehara: None. T. Ichijo: None.