Treatment for 6 months with fish oil-derived n-3 polyunsaturated fatty acids has neutral effects on glycemic control but improves dyslipidemia in type 2 diabetic patients with abdominal obesity: a randomized, double-blind, placebo-controlled trial

Purpose This study aimed to determine the effects of fish oil-derived n-3 PUFA on glycemic control and lipid profiles in type 2 diabetic patients with abdominal obesity. Methods In a randomized, double-blind, placebo-controlled trial, 100 type 2 diabetic patients with abdominal obesity were randomized into two groups including 4 g/day of fish oil (2.4 g n-3 PUFA) or placebo (corn oil) for 6 months. Serum fatty acid, body composition, as well as markers of glucose regulation and lipid parameters were measured before and after intervention. Results Thirty-five men and 64 women aged 65.4 +/- 5.3 years completed the intervention. Although body composition was unchanged, serum EPA and DHA were higher in the fish oil group than those in the placebo group (P < 0.001 and P < 0.001, respectively). Serum triglyceride (TG) decreased (P = 0.007), whereas high-density lipoprotein cholesterol (HDL-C) increased (P = 0.006) in the fish oil group compared with the placebo group after 6 months. Serum total cholesterol, low-density lipoprotein cholesterol (LDL-C), the ratio of LDL-C to HDL-C, and glycemic control (measured by serum glucose, glycated hemoglobin, insulin, and homeostasis model assessment-insulin resistance) were not significantly different between the two groups after 6 months. Conclusions This study showed that 6 months of fish oil supplement had no statistically significant effects on glycemic control, but improved TG and HDL-C in type 2 diabetic patients with abdominal obesity.