Timmers 2016.

Methods	Study design: cross‐over randomised controlled clinical trial; randomisation ratio not reported
Participants	Inclusion criteria Well‐controlled type 2 diabetes Body mass index (BMI) 27 to 35 kg/m² Age 40 to 70 years Males HbA1c < 8.0% (< 64 mmol/mL) 16 participants were treated with the oral glucose‐lowering medication metformin, 6 of whom were treated in combination with sulphonylurea derivatives Most participants received additional medications to lower cholesterol (N = 11) and/or blood pressure (N = 12) Exclusion criteria Unstable body weight (weight gain or loss > 3 kg in previous 3 months) Engagement in programmed exercise 2 hours per week Impaired renal and/or kidney function Intake of dietary supplements (except vitamins and minerals) Alcohol consumption > 20 g/d Diabetes comorbidities Insulin treatment Diagnostic criteria: not reported Setting: outpatients Age group: adults Gender distribution: males Country where study was performed: Netherlands
Interventions	Intervention(s): trans‐resveratrol Softgel Comparator(s): placebo Duration of intervention: 2 × 30 days intervention period with 30 days washout period (cross‐over study) Duration of follow‐up: 30 days Run‐in period: not reported Number of study centres: 1 Extension period: none
Outcomes	Reported outcome(s) in full text of publication: insulin sensitivity, intrahepatic lipid content, intramyocellular lipids, mitochondrial function (in vivo and ex vivo), blood pressure, and cardiac function
Study details	Trial identifier:NCT01638780 Study terminated early: no
Publication details	Language of publication: English Funding: non‐commercial funding (European Foundation for the Study of Diabetes Clinical Research Grant) Publication status: peer‐reviewed journal
Stated aim for study	Quote: "to examine if 30 days of resveratrol (resVida) supplementation leads to an improvement in peripheral and hepatic insulin sensitivity in subjects with well‐controlled T2D"
Notes	"In randomized order, participants underwent two experimental trials: a placebo and a resVida (150 mg/day trans‐resveratrol [99.9%]; provided by DSM Nutritional Products Ltd.) condition, with a washout period of at least 30 days"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote from publication: "Randomization was performed according to standard procedures as described in Statistical Methods by Snedecor and Cochran" Comment: probably performed correctly
Allocation concealment (selection bias)	Unclear risk	Comment: allocation concealment not reported
Blinding of participants and personnel (performance bias) adverse events	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of participants and personnel (performance bias) all‐cause mortality	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of participants and personnel (performance bias) fasting blood glucose	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of participants and personnel (performance bias) HbA1c	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of participants and personnel (performance bias) insulin sensitivity	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of outcome assessment (detection bias) adverse events	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of outcome assessment (detection bias) all‐cause mortality	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of outcome assessment (detection bias) fasting blood glucose	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of outcome assessment (detection bias) HbA1c	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Blinding of outcome assessment (detection bias) insulin sensitivity	Low risk	Quote from publication: "Subjects with well‐controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double‐blind crossover study for 30 days" Quote from trials register: "Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)"
Incomplete outcome data (attrition bias) adverse events	Low risk	Comment: no missing data
Incomplete outcome data (attrition bias) all‐cause mortality	Low risk	Comment: no missing data
Incomplete outcome data (attrition bias) fasting blood glucose	Low risk	Comment: no missing data
Incomplete outcome data (attrition bias) HbA1c	Low risk	Comment: no missing data
Incomplete outcome data (attrition bias) insulin sensitivity	Low risk	Comment: no missing data
Selective reporting (reporting bias)	Low risk	Comment: protocol available; outcomes reported in the protocol match the outcomes reported in the results section
Other bias	Low risk	Quote: "potential carryover effect between treatment and period was examined by unpaired t test analyses according to Pocock (29)"

Note: Where the judgement is 'Unclear' and the description is blank, the study did not report that particular outcome.

BMI: body mass index, eGFR: estimated glomerular filtration rate, GLP‐1: glucagon‐peptide 1, HbA1c: glycosylated haemoglobin A1c, IFCC: International Federation of Clinical Chemistry, WHO: World Health Organization.