Wu 2008a.

Study characteristics
Methods	Study design: Randomized controlled trial Study grouping: Parallel group How were patients recruited: The participants were recruited from the Mental Health Institute of the Second Xiangya Hospital, Central South University, P.R.China. Type of RCT: Double blind
Participants	Baseline characteristics Olanzapine plus metformin Sex (N female, %, N male, %): female 8 (44%), male 10 (55%) Age (mean, SD): 25.4 (SD 3.9) years Number of participants: 18 Olanzapine plus placebo Sex(N female, %, N male, %): female 9 (47%), male 10 (53%) Age (mean, SD): 24.8 (SD 3.5) years Number of participants: 19 Overall Sex (N female, %, N male, %): females 17 (46%), males 20 (54%) Age (range): 18 to 50 years Number of participants: 37 Inclusion criteria: Hospitalized at mental health institute, age 18 to 50 years, first psychotic episode of schizophrenia (DSM IV). Exclusion criteria: Not used any antipsychotics or recreational drugs for at least 3 months before enrollment, pregnant or lactating women and patients with mental retardation, addictive disorder, specific systemic diseases, or other medical conditions such as diabetes mellitus, dyslipidemia, cardiovascular diseases, and hypertension. Pretreatment: No statistically significant differences at baseline.
Interventions	Intervention characteristics Olanzapine plus metformin Class of drug: Antipsychotic + Antidiabetic Dose: 15 mg olanzapine + 750 mg metformin Frequency: Daily Duration: 12 weeks Who delivered the intervention: Not reported Type of intervention: Pharmacological Olanzapine plus placebo Class of drug: Antipsychotic + placebo Dose: 15 mg olanzapine + 3 placebo capsules Frequency: Daily Duration: 12 weeks Who delivered the intervention: Not reported Type of intervention: Control
Outcomes	BMI Outcome type: Continuous Reporting: Fully reported Unit of measure: kg/m2 Direction: Lower is better Data value: Change from baseline Waist circumference Outcome type: Continuous Reporting: Fully reported Unit of measure: cm Direction: Lower is better Data value: Change from baseline Fasting glucose Outcome type: Continuous Reporting: Fully reported Unit of measure: mmol/L Direction: Lower is better Data value: Change from baseline
Identification	Sponsorship source: Supported by National Key Technologies R&D Program in the 10th5‐year‐plan grant 2004BA720A22 (Dr. Zhao) from the Ministry of Science and Technology of the People’s Republic of China. Country: China Setting: Mental Health Institute Comments: ‐ Authors name: Jing‐Ping Zhao Institution: Institute of Mental Health of the Second Xiangya Hospital Email: zhaojingpinghunan@yahoo.com.cn Address: Institute of Mental Health of the Second Xiangya Hospital, Central South University, 139 Renmin Middle Road, Changsha 410011, Hunan, China
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Participants were randomly assigned (without any restriction or stratification) through a computer‐generated table to one of the two treatments (olanzapine plus metformin or olanzapine plus placebo) in blocks of four to ensure approximately equal numbers of participants within the two treatment" Judgement comment: Computer generated sequence.
Allocation concealment (selection bias)	Low risk	Quote: "To ensure concealment of the randomization, which was conducted independently of the investigators by a research phar‐ macist at a separate facility, medication was provided in coded containers containing the identical appearing pills of metformin or placebo supplied by the manufacturer."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Judgement comment: Double blinded study. No further information, but given that a placebo was used, it can be assumed that participants and personnel were blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "The research nurses who performed physical exams were blind to the patients’ treatment assignment." Judgement comment: Its not mentioned clearly whether the SAPS, SANS and treatment Emergent Symptom was applied by whom and whether that assessor was blinded or not. Probably blinded because placebo was used.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Quote: "Forty patients entered the trial. Three withdrew from the study within the first 4 weeks because of lack of re‐ sponse (one placebo patient and two metformin patients; one man and two women). This resulted in 37 (92.7%) patients who were included in the study." Judgement comment: 3 participants excluded from study because they dropped out. Authors mention analysis for completers was similar to ITT analysis. Unclear whether any other participants dropped out during the study.
Selective reporting (reporting bias)	Unclear risk	Judgement comment: No reference to protocol or trial registration.
Other sources of bias	Low risk	Judgement comment: No other sources of bias identified. Authors report no conflicts of interest.