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.