TABLE 1.

Study design of included trials that evaluated the effectiveness and safety of probiotics for glycemic control in patients with type 2 diabetes mellitus¹

Study	Interventions compared	Allowed antidiabetic standard therapy during the trial	Allowed pretreatment with antibiotics	Multi/single center trial (n, recruiting centers)	Country(ies) in which participants were recruited	Maximal planned length of follow-up, wk	Number of participants randomized
Ejtahed et al., 2011 (25)	Probiotics; control probiotics	OGM	NR	Single	Iran	6	64
Ejtahed et al., 2012 (4)	Probiotics; control probiotics	OGM	NR	Single	Iran	6	64
Tripolt et al., 2013 (26)	Probiotics; no intervention	NR	No	Single	Austria	12	30
Mazloom et al., 2013 (13)	Probiotics; placebo	NR	NR	Single	Iran	6	NR
Asemi et al., 2013 (5)	Synbiotics; prebiotics	OGM	NR	Single	Iran	8	60
Barreto et al., 2014 (27)	Probiotics; placebo	NR	NR	Single	Brazil	12	24
Shakeri et al., 2014 (28)	Probiotics; placebo	OGM	NR	Single	Iran	8	78
Mohamadshahi et al., 2014 (7)	Probiotics; control probiotics	OGM	NR	Single	Iran	8	44
Jung et al., 2014 (29)	Probiotics; no intervention	LM, OGM	NR	Single	Korea	12	48
Tajadadi-Ebrahimi et al., 2014 (30)	Probiotics; placebo	OGM	NR	Single	Iran	8	81
Ostadrahimi et al., 2015 (31)	Probiotics; control probiotics	OGM	NR	Single	Iran	8	68
Bayat et al., 2016 (32)	Probiotics; no intervention	OGM	NR	Single	Iran	8	80
Bernini et al., 2016 (33)	Probiotics; no intervention	NR	No	Single	Brazil	45 days	51
Sato et al., 2017 (34)	Probiotics; placebo	LM, OGM, insulin therapy	NR	Single	Japan	16	70
Mobini et al., 2017 (35)	Probiotics; placebo	LM, OGM, insulin therapy	No	Single	Sweden	12	46
Firouzi et al., 2017 (36)	Probiotics; placebo	LM, OGM	No	Single	Malaysia	12	136
Tonucci et al., 2017 (37)	Probiotics; control probiotics	OGM	No	Unclear2	Brazil	6	50
Feizollahzadeh et al., 2017 (38)	Probiotics; placebo	OGM, insulin therapy	No	Single	Iran	8	48
Yuan et al., 2017 (39)	Probiotics; placebo	LM, OGM, insulin therapy	No	Multi (7)	China	12	234
Raygan et al., 2018 (40)	Probiotics; placebo	OGM, insulin therapy	No	Single	Iran	12	60
Kassaian et al., 2018 (41)	Probiotics; placebo	NR	No	Single	Iran	24	120
Sabico et al., 2018 (9)	Probiotics; placebo	NR	No	Single	Saudi Arabia	6 months	96
Kobyliak et al., 2018 (12)	Probiotics; placebo	OGM, insulin therapy	No	Single	Ukraine	8	53
Hsieh et al., 2018 (6)	Probiotics; placebo	OGM, insulin therapy	No	Single	Taiwan	9 months	74
Mazruei et al., 2019 (42)	Probiotics; placebo	OGM, insulin therapy	No	Single	Iran	12	60
Naito et al., 2018 (43)	Probiotics; placebo	NR	No	Single	Japan	12	100
Razmpoosh et al., 2019 (44)	Synbiotics; prebiotics	OGM	No	Single	Iran	6	68
Khalili et al., 2019 (45)	Probiotics; placebo	OGM	No	Single	Iran	8	40

¹LM, lifestyle modification; NR, not reported; OGM, oral glucose-lowering medication.

²Participants were recruited from 2 clinics in the same city.