Spirulina is a microscopic and filamentous cyanobacterium that contains essential amino acids, essential fatty acids, vitamins, minerals and anti-oxidative components. The purpose of this study was to examine effects of spirulina intervention in Korean patients with type 2 diabetes. The subjects were 37 type 2 diabetic patients who visited a diabetic clinic in Seoul and randomly assigned into spirulina (8 g/day) or control group. During the intervention period of 12 weeks, subjects were asked to keep usual diet and prohibited to take any functional foods or dietary supplements. Spirulina supplementation for 12 weeks did not affect anthropometric parameters, however, lowered plasma triglycerides level significantly (p<0.05). Spirulina supplementation also resulted in a significant reduction in plasma malondialdehyde level (p<0.05) and an increase in plasma adiponectin level (p<0.1). The lipid lowering effect of spirulina supplementation was different according to serum lipid levels of the subjects before entering the intervention. The subjects with higher initial triglyceride level showed higher reduction in plasma triglyceride and blood pressure. The subjects with higher initial total cholesterol and LDL-cholesterol level showed higher reduction in plasma concentrations of total cholesterol, LDL-cholesterol, IL-6, and blood pressure. It seems that spirulina supplementation is more effective in subjects with dyslipidemia. This study provides the evidence for beneficial effects of spirulina supplementation on blood lipid profiles, inflammatory variables, and antioxidant capacity in Korean patients with type 2 diabetes. The results suggest that spirulina is a promising agent as a functional food for diabetes management.