Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Register of Studies Online)

1. MESH DESCRIPTOR Prediabetic state 2. MESH DESCRIPTOR Glucose Intolerance 3. (prediabet* or pre diabet*):TI,AB,KY 4. (intermediate hyperglyc?emi*):TI,AB,KY 5. ((impaired fasting ADJ2 glucose) or IFG or impaired FPG):TI,AB,KY 6. glucose intolerance:TI,AB,KY 7. ((impaired glucose ADJ (tolerance or metabolism)) or IGT):TI,AB,KY 8. ((risk or progress* or prevent* or inciden* or conversion or develop* or delay*) ADJ4 (diabetes or T2D* or NIDDM or "type 2" or "type II")):TI,AB,KY 9. #1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 10. MESH DESCRIPTOR Metformin 11. metformin*:TI,AB,KY 12. #10 OR #11 13. #9 AND #12

MEDLINE (Ovid SP)

1. Prediabetic state/ 2. Glucose Intolerance/ 3. (prediabet* or pre diabet*).tw. 4. intermediate hyperglyc?emi*.tw. 5. ((impaired fasting adj2 glucose) or IFG or impaired FPG).tw. 6. glucose intolerance.tw. 7. ((impaired glucose adj (tolerance or metabolism)) or IGT).tw. 8. ((risk or progress* or prevent* or inciden* or conversion or develop* or delay*) adj4 (diabetes or T2D* or NIDDM or "type 2" or "type II")).tw. 9. or/1‐8 10. Metformin/ 11. metformin*.tw. 12. 10 or 11 13. 9 and 12 [14‐24: Cochrane Handbook 2008 RCT filter ‐ sensitivity maximizing version] 14. randomized controlled trial.pt. 15. controlled clinical trial.pt. 16. randomi?ed.ab. 17. placebo.ab. 18. drug therapy.fs. 19. randomly.ab. 20. trial.ab. 21. groups.ab. 22. or/14‐21 23. exp animals/ not humans/ 24. 22 not 23 25. 13 and 24 26. ..dedup 25

Scopus

1. KEY("prediabetic state" OR "glucose intolerance" OR "impaired glucose tolerance") 2. TITLE‐ABS(prediabet* OR "pre diabet*" OR "intermediate hyperglyc?emi*") 3. TITLE‐ABS(("impaired fasting" PRE/3 glucose) OR IFG OR "impaired FPG") 4. TITLE‐ABS("glucose intolerance") 5. TITLE‐ABS(("impaired glucose" PRE/0 (tolerance OR metabolism)) OR IGT) 6. TITLE‐ABS((risk or progress* or prevent* or inciden* or conversion or develop* or delay*) W/4 (diabetes or T2D* or NIDDM or "type 2" or "type II")) 7. #1 OR #2 OR #3 OR #4 OR #5 OR #6 8. TITLE‐ABS‐KEY(Metformin) 9. #7 AND #8 10. TITLE‐ABS‐KEY(random* OR "clinical trial*" OR "double blind*" OR placebo*) 11. #9 AND #10 12. #11 AND (LIMIT‐TO (DOCTYPE, "ar") OR LIMIT‐TO (DOCTYPE, "ip")) [ar = article, ip = article in press]

ICTRP Search Portal (Standard search)

prediabet* AND metformin OR pre diabet* AND metformin OR impaired AND glucose* AND metformin OR impaired AND fasting* AND metformin OR glucose AND intoleran* AND metformin OR IFG AND metformin OR IGT AND metformin

ClinicalTrials.gov (Expert search)

(prediabetes OR prediabetic OR "pre diabetes" OR "pre diabetic" OR "impaired glucose" OR "impaired fasting" OR "glucose intolerance" OR IGT OR IFG OR ((diabetes OR "type 2" OR "type II" OR T2D OR T2DM) AND (risk OR progress OR progression OR progressed OR incident OR incidence OR conversion OR developed OR development OR develop OR delay OR delayed OR prevention OR prevent OR prevented))) [DISEASE] AND metformin [TREATMENT]