Metformin for Overweight & OBese ChILdren and Adolescents With BDS Treated With SGAs

Inclusion Criteria 1. Inpatient or outpatient age 8-19 years inclusive; participants must live with a parent, guardian, or caregiver; 2. Fluent in English; 3. Diagnosed or told by a clinician that they have any of the following bipolar spectrum disorders (BSD): bipolar I, bipolar II, unspecified bipolar and related disorders, Disruptive Mood Dysregulation Disorder (DMDD), cyclothymic disorder, other specified bipolar and related disorders, as well as mood disorder not otherwise specified (if diagnosed in the past as per DSM-IV); 4. Body mass index \>85%ile for age and sex by standard growth charts; 5. Received a new or ongoing prescription for at least one SGA (i.e., olanzapine, clozapine, risperidone, quetiapine, aripiprazole, ziprasidone, iloperidone, lurasidone, paliperidone, brexpiprazole or cariprazine) that is not prescribed as a PRN medication; Exclusion Criteria: 1. Patients will be excluded if they have had exposure to a total daily dose of MET 1000 mg bid for at least 2 weeks in the past 3 months; 2. Patients will be excluded if they could not tolerate MET during the recommended titration schedule outlined in the protocol; 3. Major neurological or medical illnesses that affect weight gain (e.g., unstable thyroid disease) or require a systemic medication that might impact weight or glucose regulation (e.g., diabetes mellitus \[insulin\], chronic renal failure \[steroids\]); 4. Fasting glucose ≥ 126 mg/dL on 2 occasions during screening indicating need for prompt treatment; 5. If lab results are available in the last 6 months, then a serum creatinine ≥1.3 mg/dL on 2 occasions during screening and/or follow-up, indicating potential impairment of renal functioning; 6. Pregnant or breast feeding; 7. Children and caregivers who are unable to complete assessments for any reason;