Spirulina, with its high concentration of functional nutrients, is emerging as an important therapeutic food. This study aimed to evaluate the hypoglycemic and hypolipidemic role of Spirulina. Twenty-five subjects with type 2 diabetes mellitus were randomly assigned to receive Spirulina (study group) or to form the control group. At baseline, the control and study groups were matched for various variables. The efficacy of Spirulina supplementation (2 g/day for 2 months) was determined using the preintervention and postintervention blood glucose levels, glycosylated hemoglobin (HbA(1c)) levels, and lipid profiles of the diabetic subjects. Two-month supplementation with Spirulina resulted in an appreciable lowering of fasting blood glucose and postprandial blood glucose levels. A significant reduction in the HbA(1c) level was also observed, indicating improved long-term glucose regulation. With regard to lipids, triglyceride levels were significantly lowered. Total cholesterol (TC) and its fraction, low-density lipoprotein cholesterol (LDL-C), exhibited a fall coupled with a marginal increase in the level of high-density lipoprotein cholesterol (HDL-C). As a result, a significant reduction in the atherogenic indices, TC:HDL-C and LDL-C: HDL-C, was observed. The level of apolipoprotein B registered a significant fall together with a significant increment in the level of apolipoprotein A1. Therefore, a significant and favorable increase in the ratio of A1:B was also noted. These findings suggest the beneficial effect of Spirulina supplementation in controlling blood glucose levels and in improving the lipid profile of subjects with type 2 diabetes mellitus.