This study was designed to determine changes of serum glucose and lipid levels in noninsulin dependent diabetes mellitus patients during different doses of docosahexaenoic acid (DHA)-rich fish oil supplementation. All patients had a fasting blood glucose of less than 180mg/dl, a LDL-cholesterol of less than 160mg/dl, and a triglyceride of more than 160mg/dl. None had clinical evidence of renal, hepatic or coronary vascular disease. Sixteen patients served as control. Seven patients ingested 2.00g of fish oil(low dose group), consisting of 0.30g eicosapentaenoic acid(EPA) and 0.55g DHA. The group of modest dose(n=9) was provided 3.91g of fish oil, consisting 0.59g EPA and 1.08g DHA. After 4 weeks, serum triglyceride concentration showed a mild but nonsignificant elevation in control group, a 9% decrease(194 to 177mg/dl) in the group of low dose of fish oil and a 28% decrease(206 to 161mg/dl) in the group of modest dose. The level of high density lipoprotein(HDL), HDL2, HDL3 and total cholesterol in all groups were not changed. There was a mild increase in malondialdehyde and low density lipoprotein(LDL)-cholesterol concentration and decrease in $alpha$-tocopherol concentration. However, these changes were not significant.