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	Yesa	No	Yes
Lorig et al,25 2009	Yes	Yesa	No	Yes
Dale et al,32 2009	Yes	Yes	No	Yes
Cade et al,31 2009	Yesb	Noc	Noc	Yes
Heisler et al,22 2010	Yes	Yes	Yes	Yes
Philis-Tsimikas et al,27 2011	Yes	Yesa	Noa	Yes
Smith et al,34 2011	Yes	Yes	No	Yes
Long et al,24 2012	Yes	Yes	Yes	Yes
Gagliardino et al,37 2013	Yesa	Noc	Noc	Noc
Siminerio et al,29 2013	Yes	Noa	No	Yes
Thom et al,30 2013	Yes	Yes	Noa	Yes
Chan et al,36 2014	Yes	Yes	Noc	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	Noc	Noc	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.

^aAuthor response to information requests.

^bLikely low risk of bias but no details on sequence generation available from article and author.

^cNot reported or no response from author.