In our retrospective analysis, estimated intakes of fish or DHA/EPA (n=72) as well as serum levels of DHA/EPA (n=20) are significantly correlated with HbA1c reduction by DPP-4 inhibitors in drug-naïve T2DM patients (J Diabet Investig 2012:3(5):464-7). In another retrospective analysis, serum levels of EPA are significantly correlated with HbA1c reduction by DPP-4 inhibitors in T2DM patients who received DPP-4 inhibitors as monotherapy (n=16) or add-on therapy (n=46) (J Diabet Investig 2012: 3(6):498-502).These studies support that the proposed study requires a sample size of 24 patients in each treatment group considering drop outs.