The Effects of Metformin on Glycemic Control and Insulin Sensitivity in Adolescents With T1DM

Inclusion Criteria: 1. Type 1 diabetes mellitus; 2. Age≥12 yr; 3. Tanner sexual maturation rating 2-5; 4. HbA1c levels: 7.5%-10%; 5. MDI or CSII ≥6 months; 6. Insulin dose ≥ 0.8U/kg before the enrollment，and the dosage is stable at least \>1 month（dosage change\<10%）. Exclusion Criteria: 1. Serious acute and chronic complications associated with diabetes; 2. Repeated and serious hypoglycemia episodes repeatedly; 3. Hepatic function damage (ALT≥2.5 times higher than the upper limit of the normal accepted range); 4. Moderate to advanced renal impairment (calculated according to MDRD equation: eGFR\<60ml/min/1.73m2); 5. Clinically significant heart attacks: myocardial infarction, arrhythmia，II-III°AVB，unstable angina，decompensated HF（NYHA III\~IV; 6. Female patients who have a sex life and are not willing to use contraceptive methods; 7. Pregnancy.