Efficacy and safety of metformin plus carnitine complex(Godex) compaired with metformin monotherapy in type 2 DM and impaired glucose tolerance patients with non-alcoholic fatty liver disease

INTERVENTION: Drug : 1. Combination therapy treatment group 1) Carnitine complex; carnitine orotate complex(brand name; Godex cap.), 412mg/1capsule, 2cap. tid, peroral 2) Antidiabetic; metformin HCl(brand name; Diabex tab., 250mg/1tablet, 1tab. tid, peroral 2. Monotherapy treatment group 1) Placebo; 412mg/1capsule, 2cap. tid, peroral 2) Antidiabetic; metformin HCl(brand name; Diabex tab., 250mg/1tablet, 1tab. tid, peroral CONDITION: Endocrine, nutritional and metabolic disease PRIMARY OUTCOME: The rate of ALT normalization SECONDARY OUTCOME: The changes and change rate of glycemic control (fasting glucose, fasting insulin, HbA1c) The changes of mitochondria DNA copy number The changes of plasma ALT levels The changes of urine 8‐OHdG INCLUSION CRITERIA: 1) Age at least 18 years and under 80 years 2) Subjects with non‐alcoholic fatty liver disease; 35U/L = ALT = 250u/L 3) 100mg/dL = fasting glucose = 300mg/dL or HbA1c > 6.5% 4) Able and willing to provide informed consent