Table 1 Study Characteristics
| Study | Methods | Participants | Country | Numbers | Intervention | |
|---|---|---|---|---|---|---|
| 1. | Armen 2008 |
Parallel group RCT Duration 12 weeks |
Age < 20 years On risperidone 2–6 mg | Saudi Arabia |
Metformin N = 16 Placebo N = 16 | Metformin 500 mg twice daily or placebo |
| 2. | Baptista 2006 |
Parallel group RCT Duration 14 weeks |
Age ≥18 years Olanzapine monotherapy > 4 months | Venezuela |
Metformin N = 19 Placebo N = 18 |
Metformin 850–1750 mg Balanced diet of 2500-300Kcal |
| 3. | Baptista 2007 |
Parallel group RCT Duration 12 weeks |
Age ≥18 years Olanzapine monotherapy > 4 months | Venezuela |
Metformin N = 36 Placebo N = 36 |
Metformin 850–2550 mg or placebo Diet and exercise counseling at start of study |
| 4. | Carrizo 2009 |
Parallel group RCT Duration 14 weeks | clozapine treatment > 3 months | Venezuela |
Metformin N = 31 Placebo N = 30 | Extended release metformin 500–1000 mg/day or placebo |
| 5. | Chen |
Parallel group RCT Duration 24 weeks |
clozapine treatment > 3 months BMI ≥24 or one metabolic syndrome criteria | Taiwan |
Metformin N = 28 Placebo N = 27 | Metformin 1500 mg/day |
| 6. | De Silva 2015 |
Parallel group RCT Duration 24 weeks |
Age ≥18 years Weight gain > 10 % of body weight Females 78.8 % | Sri Lanka |
Metformin N = 34 Placebo N = 32 |
Metformin or placebo 500 mg twice daily Diet and exercise counseling given at start of study |
| 7. | Jarskog 2013 |
Parallel group RCT Duration 16 weeks |
Age 18–65 years BMI ≥27 Duration of illness ≥ 1 year Females 30.8 % | United States |
Metformin N = 75 Placebo N = 71 |
Metformin 500 mg twice daily increased upto maximum of 2000 mg/day or placebo Weekly diet and exercise counseling |
| 8. | Klein |
Parallel group RCT Duration 16 weeks |
Age 10–17 years Gained > 10 % body weight | United States |
Metformin N = 34 Placebo N = 32 |
Metformin 850 mg twice daily or placebo nutritional counseling |
| 9. | Wang 2012 |
Parallel group RCT Duration 12 weeks |
Age 18–60 years Gained > 7 % of body weight | China |
Metformin N = 32 Placebo N = 34 | Metformin 500 mg twice daily or placebo |
| 10. | Wu 2012 |
Parallel group RCT Duration 24 weeks |
Age 18–40 years First episode Female patients only | China |
Metformin N = 42 Placebo N = 42 | Metformin 1000 mg/day or placebo |
| 11. | Wu 2008a JAMA |
Parallel group RCT Duration 12 weeks |
Age 18–45 years First episode patient who gained > 10 % of bodyweight | China |
Metformin N = 32 Placebo N = 32 |
Metformin 750 mg or placebo (also metformin + lifestyle and lifestyle + placebo groups) |
| 12. | Wu 2008b AM J |
Parallel group RCT Duration 12 weeks |
Age 18–50 years First episode patients on olanzapine | China |
Metformin N = 18 Placebo N = 19 |
Metformin 250 mg thrice daily or placebo No special diet or exercise program |