| Study | Reason for exclusion |
|---|---|
| Anderson 2016 | Review |
| Anonymous 2014 | Not a randomised controlled trial |
| Australian Prescriber 2013 | Not a randomised controlled trial |
| Australian Prescriber 2014 | Not a randomised controlled trial |
| Bailey 2015 | Non‐concomitant interventions |
| Belcher 2004 | Review |
| Belcher 2005a | Review |
| Belcher 2005b | Review |
| Billington 2015 | Systematic review/meta‐analysis |
| Borges 2011 | Comparator arm included metformin |
| Boussageon 2012 | Systematic review/meta‐analysis |
| Boussageon 2016 | Review |
| Bruce 2006 | Intervention 20 weeks |
| Buhse 2016 | Systematic review/meta‐analysis |
| Cai 2016 | Systematic review/meta‐analysis |
| Ceriello 2005 | Review |
| Chanson 2014 | Review |
| Chen 2016 | Randomisation of participants to comparator comprising multiple glucose‐lowering interventions reported as one |
| Cheng 2017 | Systematic review/meta‐analysis |
| ChiCTR‐IOR‐16009296 | Intervention 4 months |
| ChiCTR‐IPR‐16008578 | Intervention 24 weeks |
| ChiCTR‐IPR‐17010825 | Intervention 24 weeks |
| ChiCTR‐IPR‐17011120 | Inclusion only of participants with intercurrent polycystic ovarian syndrome |
| ChiCTR‐TRC‐08000231 | Intervention 48 weeks |
| ChiCTR‐TRC‐11001613 | Inclusion only of participants with chronic heart failure in addition to T2DM |
| ChiCTR‐TRC‐11001808 | Intervention 24 weeks |
| ChiCTR‐TRC‐12002320 | Intervention 12 weeks |
| ChiCTR‐TRC‐12002505 | Intervention 3 months |
| ChiCTR‐TRC‐13003368 | Intervention 12 weeks |
| ChiCTR‐TRC‐14004660 | Inclusion only of participants with intercurrent non‐alcoholic fatty liver disease in addition to T2DM |
| Clarke 1968 | Randomisation of participants to first‐generation sulphonylurea |
| Clarke 1977 | Randomisation of participants to first‐generation sulphonylurea |
| Clarke 2001 | The glycaemic target was different between the metformin arm and conventional therapy. The sulphonylurea‐ and insulin arm had the same glycaemic target as the metformin arm, but data were not reported |
| Coleman 2015 | Review |
| Cooper 2015 | Review |
| Cryer 2005 | Study drug used in the comparator arm determined by study investigators |
| Dalzell 1986 | Randomisation of participants to first‐generation sulphonylurea |
| EUCTR2005‐001027‐11‐GB | Intervention less than 52 weeks due to premature termination |
| EUCTR2007‐006665‐33‐DK | Intervention less than 52 weeks |
| EUCTR2012‐001390‐88‐CZ | Intervention 3 months |
| Ferrannini 2013 | Non‐concomitant comparator |
| Gallo 2014 | Intervention 48 weeks |
| Garcia 2014 | No participants randomised to metformin monotherapy |
| Gu 2014 | Systematic review/meta‐analysis |
| Haak 2013 | No participants randomised to metformin monotherapy |
| Heitmann 2016 | Review |
| Hirst 2012 | Systematic review/meta‐analysis |
| Holden 2014 | Review |
| Hong 2013 | Inclusion of participants with coronary artery disease in addition to T2DM |
| Hou 2017 | Systematic review/meta‐analysis |
| Hwang 2015 | Systematic review/meta‐analysis |
| Ida 2017 | Systematic review/meta‐analysis |
| ISRCTN75451837 | Not a randomised controlled trial |
| JPRN‐UMIN000004367 | Participants continued prior glucose‐lowering drugs |
| JPRN‐UMIN000005327 | Participants continued prior glucose‐lowering drugs |
| JPRN‐UMIN000011063 | Intervention 12 weeks |
| Kakorin 2016 | Review |
| Kanazawa 2009 | Participants continued prior glucose‐lowering drugs |
| Lambadiari 2018 | Intervention 6 months |
| Lester 2005 | Not a randomised controlled trial |
| Liakos 2014 | Systematic review/meta‐analysis |
| Liu 2014 | Systematic review/meta‐analysis |
| Liu 2014a | Systematic review/meta‐analysis |
| Liu 2017 | Systematic review/meta‐analysis |
| MacConell 2015 | Post‐hoc analysis |
| Mei 2014 | Systematic review/meta‐analysis |
| MET/D/86/BERGI 1994 | Study never published. Unknown design |
| Mo 2019 | Intervention 48 weeks |
| Monami 2014 | Systematic review meta‐analysis |
| NCT00214591 | Tesaglitazar in developmental phase |
| NCT00282945 | Intervention 6 months |
| NCT00308373 | Intervention 4 months |
| NCT00373178 | Intervention 14 weeks |
| NCT00396851 | Withdrawn due to lack of funding |
| NCT00399204 | Withdrawn due to lack of funding |
| NCT00481663 | Non‐concomitant interventions |
| NCT00543361 | Comparator is not an approved drug (MK0767) |
| NCT00754689 | Comparator is not a recognised drug (rimonabant) |
| NCT01087567 | Intervention 6 months |
| NCT01099618 | Inclusion only of participants with diabetic ketoacidosis in addition to T2DM |
| NCT01217073 | No randomisation to metformin |
| NCT01700075 | Participants with T2DM not included |
| NCT01958671 | Metformin intervention does not last for 52 weeks |
| NCT02234440 | Inclusion only of participants with intercurrent non‐alcoholic steatohepatitis |
| NCT02409238 | Participants with T2DM not included |
| NCT02587741 | Metformin in all interventions |
| NCT02694289 | Withdrawn due to failure to enrol participants |
| Palmer 2016 | Systematic review/meta‐analysis |
| Polzer 2015 | Intervention 16 weeks |
| Prescrire International 2014 | Review |
| Prescrire International 2015 | Review |
| Rokkas 2016 | Systematic review/meta‐analysis |
| Rosenstock 2013 | Non‐concomitant intervention |
| Rutter 2010 | Study drug used in the comparator arm determined by study investigators |
| Salpeter 2003 | Systematic review/meta‐analysis |
| Sazia 2015 | Intervention of 3 months |
| Scheen 2016 | Not a randomised controlled trial |
| Scheen 2017 | Not a randomised controlled trial |
| The Medical Letter 2015 | Not a randomised controlled trial |
| UKPDS 24 | Data reported after 6 years of follow‐up where approximately 70% of the participants in each intervention arm received combination therapy |
| UKPDS 72 | Comparator arm had a different glycaemic target from the one in the intervention arm |
| Unnikrishnan 2016 | Review |
| Yang 2014 | Intervention 48 weeks |
| Zhang 2015 | Systematic review/meta‐analysis |
| Zhang 2016 | Systematic review/meta‐analysis |
| Zhou 2017 | Systematic review/meta‐analysis |
| Zintzaras 2014 | Systematic review/meta‐analysis |
T2DM: type 2 diabetes mellitus.