Table 2

Quality of the Included Studies Assessed With the Cochrane Risk of Bias Tool¹²

Study, Year	Adequate Sequence Generation	Allocation Concealment	Blinding of Investigators and/or Outcome Assessors	Complete Outcome Data
Keyserling et al,²³ 2002	Yes	Yes	No	Yes
Lorig et al,²⁶ 2008	Yes	Yes^a	No	Yes
Lorig et al,²⁵ 2009	Yes	Yes^a	No	Yes
Dale et al,³² 2009	Yes	Yes	No	Yes
Cade et al,³¹ 2009	Yes^b	No^c	No^c	Yes
Heisler et al,²² 2010	Yes	Yes	Yes	Yes
Philis-Tsimikas et al,²⁷ 2011	Yes	Yes^a	No^a	Yes
Smith et al,³⁴ 2011	Yes	Yes	No	Yes
Long et al,²⁴ 2012	Yes	Yes	Yes	Yes
Gagliardino et al,³⁷ 2013	Yes^a	No^c	No^c	No^c
Siminerio et al,²⁹ 2013	Yes	No^a	No	Yes
Thom et al,³⁰ 2013	Yes	Yes	No^a	Yes
Chan et al,³⁶ 2014	Yes	Yes	No^c	Yes
Simmons et al,³³ 2015	Yes	Yes	Yes	Yes
Safford et al,²⁸ 2015	Yes	Yes	No	Yes
Ayala et al,²¹ 2015	Yes	No^c	No^c	Yes
McGowan,³⁵ 2015	Yes	Yes	No	Yes

Notes: Yes indicates low risk of bias; No indicates high risk of bias. Selective outcome reporting risk was considered minimal as we selected only studies that reported hemoglobin A_1c level as the outcome. No other major biases were noted in the included studies. None of the trials blinded participants.
↵a Author response to information requests.
↵b Likely low risk of bias but no details on sequence generation available from article and author.
↵c Not reported or no response from author.