Anand 2011.

Methods	2‐arm, open‐label RCT, with 3 months duration of treatment and follow‐up.
Participants	Location: Ootacamund, Tamil Nadu India. Single centre Recruitment: outpatient department, Government headquarters hospital, Ootacamund Sample size: Number randomised: 38 in intervention, 36 in comparison Number completed: 38 in intervention, 36 in comparison Participant baseline characteristics: Age: mean 54.65 ± 8.44 intervention and 56.61 ± 8.17 in comparison Total MMSE: 25.16 ± 0.66 in intervention, 25.3 ± 0.37 in comparison Gender: male/female 15/23 intervention and 14/22 in comparison Others: Most of the participants were from an economically deprived background, non‐vegetarians. Inclusion criteria: Type 2 diabetes with no comorbidities Age between 35 and 65 of either sex On oral hypoglycaemic agents (metformin, glibenclamide and combination) Duration of disease less than or equal to 10 years HbA1c > 9% Exclusion criteria: Dementia Antidepressant therapy Type 1 diabetes Juvenile diabetes Pregnancy/lactation Significant hepatic and renal dysfunction
Interventions	Intervention group (n = 38): vitamin E 600 mg once daily for three months Comparator group (n = 36): treatment‐as‐usual for three months Treatment received by both groups: oral hypoglycaemic agents (glibenclamide 5 mg, metformin 500 mg) for three months
Outcomes	Outcomes of interest in the review: Cognitive outcome: MMSE (Tamil version); MMSE 18–23 classified as MCI and 24‐30 classified as no cognitive impairment
Notes	Funding Sources: "Nil". Declarations of interest: none declared. Other: population was from a government hospital clinic in India and "most of the enrolled patients were coming under economically deprived background."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Enrolled patients were randomized by using computer assisted randomization procedure and assigned to control group and intervention group" Comment: adequate generation of a randomised sequence
Allocation concealment (selection bias)	Unclear risk	Comment: no description of allocation concealment. The study was open‐label. Unknown whether allocation for the next patient to be enrolled could be known in advance.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "open‐label trial" Comment: did not describe control group receiving placebo of Vitamin E. No description of blinding and described as an 'open‐label' study.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Comment: no description of measures used, if any, to blind personnel involved in measuring outcomes. Since outcome measures depended on patient performance, risk of bias was judged to be high.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: There was no description of the completeness of outcome data for each main outcome, nor of exclusions from the analysis.
Selective reporting (reporting bias)	Low risk	Comment: no evidence of selective reporting bias
Other bias	Low risk	No other risk of bias detected.