The purpose of this study is to verify the possible effects of OMACOR(omega-3 fatty acid) on the percentage change of small dense LDL fraction in type 2 diabetic patients with combined hyperlipidemia, we perform open-label prospective randomized multi-institutional phase IV study.

The main cause of mortality in type 2 diabetes mellitus is a cardiovascular disease. Among the many risk factors of atherosclerosis in diabetic patients, LDL(low density lipoprotein) cholesterol is now being regarded as one of the most important modifiable one. Recent researches have revealed that the plasma LDL could be sub-divided according to the size of the particles into large buoyant LDL and small dense LDL. Small dense LDL is very atherogenic. Increased plasma triglyceride and the presence of insulin resistance are proved to be positively correlated well with the amount of small dense LDL in diabetic patients.

We would like to see omega-3 acid(OMACOR) which is now widely used in clinical practice to decrease plasma triglyceride could change the amount of plasma small dense LDL in type 2 diabetic patients with combined hyperlipidemia.

This trial is consisted of 6 weeks of wash out for the patients already taking statin. After that, daily 4 grams of omega-3 acid(OMACOR) will be administered for 10 weeks. Before and after the administration of study drug, we will measure the change of the amount of plasma small dense LDL via ultracentrifuge/non-denaturing polyacrylamide gel electrophoresis followed by oil red O and coomassie blue staining. As a secondary outcome measure, we will also assess the change of HDL(high density lipoprotein) cholesterol sub-type by the same method.

Inclusion Criteria:

• Agreed for informed consent
• Age between 40-70 years old
• Type 2 diabetes mellitus
• Combined hyperlipidemia
• Serum triglyceride level between 200-500(mg/dl)
• No sudden change of glucose lowering therapies during trial, anticipated

Exclusion Criteria:

• Hypersensitivity to OMACOR(Omega-3 fatty acid)
• Alcoholics
• Pregnancy
• Proliferative diabetic retinopathy
• Patients already taking fibrates
• Enrolled in other clinical trials during the recent 3 months
• Severe ischemic heart disease, liver disease, neurological disease
• AST/ALT level 2 folds above the normal reference level
• Psychiatric disorder not adequately controlled
• Serum creatinine over 2.0 (mg/dl)
• Previous pancreatic surgery
• Patients who can not maintain regular diet