Ludvik 2002.

Methods	Parallel RCT Randomisation ratio: 1:1 Superiority design
Participants	Inclusion criteria: clinically stable T2DM on diet only Exclusion criteria: no information Diagnostic criteria: authors' criteria
Interventions	Number of study centres: no information Treatment before study: diabetic diet Titration period: nil Experimental intervention groups: Tablets each containing 168 mg powdered white‐skinned sweet potato (Ipomoea batatas) Tablets each containing 336 mg powdered white‐skinned sweet potato (Ipomoea batatas Participants in each group received 4 tablets 3 times daily after meals for a period of 6 weeks. A total of 2 g and 4 g/day were ingested by participants in each group, respectively Control intervention: Placebo tablets. No information on the contents of these tablets All patients were on diet regimen during the study
Outcomes	Outcomes reported in abstract of publication: Primary outcome(s): (as stated in the publication) change in fasting blood glucose Seondary outcome(s): (as stated in the publication) change in plasma insulin level, serum cholesterol and weight Additional outcome(s): incidence of adverse events
Study details	Run‐in period: no information Was s tudy terminated early (for benefit/because of adverse events): no
Publication details	Language of publication: English Commercial funding: grant from manufacturer Publication status: peer review journal
Stated aim of study	Quote from publication: "To assess the effect of caiapo on glucose metabolism, its tolerability and mode of action in male Caucasian type 2 diabetic patients".
Notes	Letter to editor. Pilot study
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote from publication: "randomised to receive placebo or 2 (low dose) or 4 g (high dose) caiapo" Comment: there was no description of generation of the random sequence; furthermore, reports of 2 other trials by the same principal investigators that used a similar intervention also provided no information about sequence generation
Allocation concealment (selection bias)	Unclear risk	Comment: there was no information provided about the method of allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote from publication: "double‐blind" Comment: there was no other information available concerning blinding
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: fasting blood glucose was specifically accessed at each visit for each participant
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: all participants completed the study, no treatment withdrawals or major adverse events reported
Selective reporting (reporting bias)	Low risk	Comment: primary outcomes were stated
Other bias	Unclear risk	Comment: there was no information about the sample size calculation or exclusion criteria; there was also insufficient information to assess other important risks of bias