Mauras 2012.

Methods	Parallel randomised controlled clinical trial, randomisation ratio 1:1, superiority design
Participants	Inclusion criteria: uncomplicated (exogenous) obesity defined as BMI > 95th percentile for US standards for < 5 years normal blood pressure, glucose tolerance and total cholesterol Exclusion criteria: chronic illness, medications, alcohol use and smoking Diagnostic criteria: see above
Interventions	Intervention: metformin + diet/exercise intervention Comparator: diet/exercise intervention Number of trial centres: 1 Treatment before trial: no Titration period: metformin was started at 250 mg orally, twice daily, before meals titrating up to 500 mg twice daily in children < 12 years old and 1000 mg twice daily as tolerated in older children
Outcomes	Outcomes reported in abstract of publication: weight loss, hsCRP, fibrinogen, intrahepatic fat
Study details	Run‐in period: no Trial terminated early: no
Publication details	Language of publication: English Noncommercial funding Publication status: peer‐reviewed journal
Stated aim for study	Quote from publication: "To determine if metformin improves markers of inflammation, thrombosis, and intrahepatic fat contents in children with uncomplicated obesity"
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote (from the author): "randomisation assignments were balanced for pubertal status. We used sealed envelopes with equal amount of labels organized at random for pubertal and pre‐pubertal kids to choose from at their CRC visit (baseline)" Comment: adequate randomisation process
Allocation concealment (selection bias)	Low risk	Comment: the author of the trial confirmed allocation was concealed via the sealed envelopes
Blinding of participants and personnel (performance bias) Objective outcomes	High risk	Comment: no placebo was given to the control group, therefore the participants would not have been blinded
Blinding of participants and personnel (performance bias) Subjective outcomes	High risk	Comment: no placebo was given to the control group, therefore the participants would not have been blinded
Blinding of outcome assessment (detection bias) Objective outcomes	High risk	Comment: author confirmed the outcome assessors were not blinded
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Comment: author confirmed the outcome assessors were not blinded
Incomplete outcome data (attrition bias) Objective outcomes	High risk	Comment: there was a high number of dropouts and no imputation method was used to replace missing data
Incomplete outcome data (attrition bias) Subjective outcomes	High risk	Comment: there was a high number of dropouts and no imputation method was used to replace missing data
Selective reporting (reporting bias)	Low risk	Quote: "The study was registered at http://www.clinicaltrials.gov (NCT00139477)" Comment: all outcomes reported on the clinical trial register page were reported in the publication
Other bias	Unclear risk	Comment: unable to access if any other bias were present