Table 1: Characteristics of the 14 trials included in the meta-analysis.

Trial	Location	Design	Treatment; no. of patients			Duration of intervention
			Sulfonylurea	Metformin	Total
ADOPT, 200620–26	North America, Europe and Canada	Parallel; blinding of investigators and participants	1447	1455	2902	4 yr
Campbell et al., 199427	United Kingdom	Parallel; open label	24	24	48	1 yr
Collier et al., 198928	NR	Parallel; open label	12	12	24	6 mo
DeFronzo et al., 199529	United States	Parallel; blinding of investigators and participants	209	210	419	29 wk
Derosa et al., 200442	Italy	Parallel; open label	81	83	164	12 mo (+ 8-wk titration period)
Hermann et al., 1991a30	Sweden	Crossover; open label	10*	12*	25*	6 mo
Hermann et al., 1991b31–34	Sweden	Parallel; blinding of investigators and participants	34	38	72	6 mo + 2–12 wk titration period
Kamel et al., 199735	Turkey	Parallel; blinding of investigators and participants	17†	6	23	24 wk
Lawrence et al., 200436	United Kingdom	Parallel; open label	22	21	43	24 wk
Tang et al., 200441	China	Parallel; open label	33	29	62	6 mo
Tessier et al., 199937	Canada	Parallel; open label	19	20	39	24 wk
Tosi et al., 200338	Italy	Crossover; blinding of investigators and participants	22	22	44	6 mo
UKPDS 34, 19982,39,40	United Kingdom	Parallel; open label	277	342	619	10.7 yr
Yamanouchi et al., 200543	Japan	Parallel; NR (we assume open label)	37	39	76	12 mo

Note: ADOPT = A Diabetes Outcome Progression Trial, NR = not reported, UKPDS = United Kingdom Prospective Diabetes Study. 
*Number of participants randomly selected for each intervention arm not reported; only those who completed the trial.
†The 17 participants in the sulfonylurea arm were given either gliclazide (9 participants) or glibenclamide (8 participants).