Characteristic	Intervention(s) and comparator(s) [dosage per day]	Duration of intervention (duration of follow‐up)	Participating population	Study period [year to year]	Country	Setting	Duration of diabetes [mean years (SD)]
Ludvik 2002	I1: sweet potato (Caiapo) tablets 2 g	6 weeks (6 weeks)	Male participants with T2DM on diet	‐	Austria	‐	‐
	I2: sweet potato (Caiapo) tablets 4 g	6 weeks (6 weeks)
	C: placebo	6 weeks (6 weeks)
Ludvik 2004	I: sweet potato (Caiapo) tablets 4 g	3 months (3 months)	People with T2DM on diet	‐	Switzerland	Outpatients (offices of general practitioners)	‐
	C: placebo	3 months (3 months)
Ludvik 2008	I: sweet potato (Caiapo) tablets 4 g	5 months (5 months)	People with T2DM	‐	Austria and Germany	Outpatients clinics	3.5 (4.2)
	C: placebo	5 months (5 months)					4.2 (2.9)
Footnotes "‐" denotes not reported C: comparator; I: intervention; SD: standard deviation; T2DM: type 2 diabetes mellitus