Characteristic	Hamilton 2003	Sarnblad 2003
Intervention 1 (I1) / intervention 2 (I2) / control 1 (C1)	I1: oral metformin added to s.c. insulin C1: placebo added to s.c. insulin	I1: oral metformin added to s.c. insulin C1: placebo added to s.c. insulin
Randomised controlled clinical trial (RCT)	Y	Y
Non‐inferiority / equivalence trial	N	N
Controlled clinical trial	Y	Y
Design: parallel, crossover, factorial RCT	parallel	parallel
Design: crossover study
Design: factorial study
Crossover study: wash‐out phase
Crossover study: carryover effect tested
Crossover study: period effect tested
Method of randomisation (specify)	Y: computer generated block random number table	??
Unit of randomisation (individuals, cluster ‐ specify)	Individual block randomization by sex and pubertal status	Individual stratified according to gender
Randomisation stratified for centres	N	N
Randomisation ratio	1:1	1:1
Concealment of allocation (specify)	Y clear adequate	?
Stated blinding (open; single, double, triple blind)	double	double
Actual blinding: participant	?	?
Actual blinding: caregiver / treatment administrator	?	??
Actual blinding: outcome assessor	?	?
Actual blinding: others	?	?
Blinding checked: participant	?	?
Blinding checked: caregiver / treatment administrator	?	?
Primary endpoint defined	N	Y (HbA1c)
[n] of primary endpoint(s)	not specified	1
[n] of secondary endpoints	not specified	8
Total [n] of endpoints	13	9
Prior publication of study design	?	?
Outcomes of prior and current publication identical	?	?
Power calculation	Y: <80%?	Y: <80%?
[n] participants per group calculated	I: 14 C: 13	I: 16 C: 14
Non‐inferiority trial: interval for equivalence specified
Intention‐to‐treat analysis (ITT)	N	N
Per‐protocol‐analysis	Y	Y
ITT defined	N	N
Missing data: last‐observation‐carried‐forward (LOCF)	N	N
Missing data: other methods	N	N
LOCF defined	N	N
[n] of screened participants (I1/ I2 / C1 / total)	?	?
[n] of randomised participants (for primary endpoint)	I1: 15 C1: 15 Total: 30	I1: 16 C1: 14 Total: 30
[n] of participants finishing the study	27	24
[n] of patients analysed (for primary endpoint)	27	26
Description of discontinuing participants	Y	Y
Drop‐outs (reasons explained)	Y	Y
Withdrawals (reasons explained)	Y	Y
Losses‐to‐follow‐up (reasons explained)	Y	Y
[n] of participants who discontinued	3	6
[%] discontinuation rate	3/30= 10%	6/30=20%
Discontinuation rate similar between groups	N I:1(6.7%) C:2 (13.4%)	N I:5/16: 31% C:1/14: 7%
[%] crossover between groups	N	N
Differences [n] calculated to analysed patients	7	7
Adjustment for multiple outcomes / repeated measurements	N	N
Baseline characteristics: clinically relevant differences	N	N
Treatment identical (apart from intervention)	Y	Y
Compliance measured	Y	Y
Other important covariates measured (specify)	N	N
Co‐morbidities measured	N	N
Co‐medications measured	N	N
Specific doubts about study quality	N	Y: method of randomisation not specified, allocation concealment not mentioned, attrition bias (drop‐out: 20%), detection bias (outcome assessors not mentioned to be blind)
Funding: commercial	Y: grants from the Hospital for Sick Children Research Institute and the Order of the Eastern Star of Ontario	N
Funding: non‐commercial	Y: Drug and Placebo were provided by Aventis Pharma	Y: Drug and Placebo were provided by Merck AB, Pharma division
Publication status: peer review journal	Y	Y
Publication status: journal supplement	N	N
Publication status: abstract	N	N
Publication status: other	N	N
Footnotes: Y = yes; N = no; ? = unclear I = intervention; C = control