Trial ID	Outcome	High risk of bias (category A)a	High risk of bias (category D)b	High risk of bias (category E)c	High risk of bias (category G)d
Bilezikian 2013	Anthropometric measures	No	No	Yes	No
	Intervention failure	No	Yes	No	No
Campbell 1994	Lactic acidosis	No	No	No	Yes
	Serious adverse events	No	Yes	No	No
	Severe hypoglycaemia	No	Yes	No	No
Derosa 2003	All‐cause mortality	No	No	Yes	No
	Anthropometric measures	No	Yese	No	No
	Glycaemic control	No	Yese	No	No
Derosa 2004	ND
Derosa 2009	All‐cause mortality	No	No	Yes	No
	Serious adverse events	No	Yese	No	No
	Severe hypoglycaemia	No	Yese	No	No
	Glycaemic control	No	Yese	No	No
	Anthropometric variables	No	Yese	No	No
Erem 2014	ND
Kahn 2006	Health‐related quality of life	No	Yes	No	No
Kiyici 2009	ND
Onuchin 2010	All‐cause mortality	No	No	Yes	No
	Serious adverse events	No	No	Yes	No
	Severe hypoglycaemia	No	No	No	Yes
Pfützner 2011	Anthropometric measures	No	Yese	Yes	No
Rahman 2011	All‐cause mortality	No	No	Yes	No
	Serious adverse events	No	No	Yes	No
Schernthaner 2004	Serious adverse events	No	No	Yes	No
	Anthropometric measures	No	Yese	Yes	No
Schweizer 2007	Non‐fatal myocardial infarction	No	No	No	Yes
	Serious adverse events	No	Yese, f	No	No
	Severe hypoglycaemia	No	Yese, f	No	No
	Glycaemic controlg	No	Yese	No	No
	Anthropometric measuresg	No	Yese	No	No
	Intervention failure	No	No	Yes	No
Teupe 1991	All‐cause mortality	No	No	Yes	No
	Serious adverse events	No	No	Yes	No
	Lactic acidosis	No	No	No	Yes
UKPDS 34 1998	All‐cause mortality	No	Yes	No	No
	Serious adverse events	No	Yes	No	No
	Health‐related quality of life	No	Yes	No	No
	Cardiovascular mortality	No	Yes	No	No
	Non‐fatal myocardial infarction	No	Yes	No	No
	Non‐fatal stroke	No	Yes	No	No
	End‐stage renal disease	No	Yes	No	No
	Blindness	No	Yes	No	No
Umpierrez 2014	ND
Williams‐Herman 2010	Intervention failure	No	Yese	No	No
Yamanouchi 2005	All‐cause mortality	No	No	Yes	No
	Serious adverse events	No	No	Yes	No
	Severe hypoglycaemia	No	No	No	Yes
aClear that outcome was measured and analysed; trial report states that outcome was analysed but reports only that result was not significant (Classification 'A', table 2, Kirkham 2010) bClear that outcome was measured and analysed; trial report states that outcome was analysed but report no results (Classification 'D', table 2, Kirkham 2010) cClear that outcome was measured but was not necessarily analysed; judgement says likely to have been analysed but not reported due to non‐significant results (Classification 'E', table 2, Kirkham 2010) dUnclear whether outcome was measured; not mentioned, but clinical judgement says likely to have been measured and analysed but not reported on the basis of non‐significant results (Classification 'G', table 2, Kirkham 2010) eOutcome reported in an inadequate format that could not be used in our meta‐analysis fUnclear whether participants with the outcomes in the initial 52‐week study were being added to the results from the extension period gOutcomes measured in the extension period of 52 weeks ND: none detected; ORBIT: Outcome Reporting Bias In Trials; UKPDS: United Kingdom Prospective Diabetes Study.