Atabek 2008.

Methods	Parallel randomised controlled trial, randomisation ratio 3:1 (intervention:control), superiority design
Participants	Inclusion criteria: BMI ≥ 95th percentile for age and sex based on the standards of the CDC Exclusion criteria: children were excluded if they had prior major illness, including type 1 or type 2 diabetes mellitus took medications or had a condition known to influence body composition, insulin action, or insulin secretion none of the participants had a history of diabetes mellitus Diagnostic criteria: see above
Interventions	Intervention: metformin + diet and physical activity advice Comparator: placebo + diet and physical activity advice Number of trial centres: 1 Treatment before trial: none Titration period: no
Outcomes	Outcomes reported in abstract of publication: BMI, fasting insulin, 120‐min insulin levels, FGIR, HOMA‐IR, QUICKI
Study details	Run‐in period: no Trial terminated early: no
Publication details	Language of publication: English Funding: no information given Publication status: peer‐reviewed journal
Stated aim for study	Quote from publication: "To determine whether metformin treatment for 6 months is effective in reducing body weight and hyperinsulinaemia and also ameliorating insulin sensitivity indices in obese adolescents with hyperinsulinaemia"
Notes	‐
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: no description of randomisation process
Allocation concealment (selection bias)	Unclear risk	Comment: no description of how allocation was concealed
Blinding of participants and personnel (performance bias) Objective outcomes	Unclear risk	Quote: "a 6 month, randomized, double‐blind placebo‐controlled, parallel‐group, prospective clinical trial" Comment: unsure who was blinded
Blinding of participants and personnel (performance bias) Subjective outcomes	Unclear risk	Quote: "a 6 month, randomized, double‐blind placebo‐controlled, parallel‐group, prospective clinical trial" Comment: unsure who was blinded
Blinding of outcome assessment (detection bias) Objective outcomes	Unclear risk	Quote: "a 6 month, randomized, double‐blind placebo‐controlled, parallel‐group, prospective clinical trial." Comment: unsure who was blinded
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Quote: "a 6 month, randomized, double‐blind placebo‐controlled, parallel‐group, prospective clinical trial" Comment: unsure who was blinded
Incomplete outcome data (attrition bias) Objective outcomes	Unclear risk	Comment: the trial did not report the number of dropouts, or clarify there were no dropouts
Incomplete outcome data (attrition bias) Subjective outcomes	Unclear risk	Comment: the trial did not report the number of dropouts, or clarify there were no dropouts
Selective reporting (reporting bias)	High risk	Quote: "A detailed questionnaire on food consumption was completed at the beginning and at the end of the trial medication period" Comment: no results shown for food consumption data. Also, very unclear on the number lost to follow‐up and what type of analyses were conducted
Other bias	High risk	Comment: there was uncertainty to whether this was a randomised controlled trial or a matched controlled trial. Concern arose over a lack of description about randomisation, blinding and allocation. No rationale for the size of intervention group and no calculation of power. They also do not declare who funded the trial