In order to test whether hyperlipidaemia and glycaemic control can be improved among diabetes patients by dietary supplementation with purified omega-3 fatty acids, we carried out a double-blind, placebo-controlled trial on 50 type 2 diabetes patients randomized to 2 g/day purified omega-3 fatty acids or placebo for 10 weeks. Fasting triglycerides decreased significantly with supplementation relative to placebo (P = 0.01). There was a significant decrease in ApoB-100 and malondialdehyde compared to baseline values and compared to the control group. Omega-3 fatty acids had no significant effect on serum lipid levels, ApoA-I, glucose, insulin and HbA1c.