Sugiyama 2015.

Study characteristics
Methods	Effect of a community‐based diabetes self‐management empowerment program on mental health‐related quality of life: a causal mediation analysis from a randomized controlled trial RCT (NA clusters and NA providers), conducted in 1) Community‐based diabetes self‐management education (DSME) intervention (senior centres, churches, community clinics, and Los Angeles County Community and Senior Service Centers). 2) Intervention provided by health educators. In United States of America. 2 arms: 1. Control (unrelated lectures) (control arm) and 2. Intervention (community‐based DSME) (intervention arm)
Participants	Control arm N: 258 Intervention arm N: 258, NA, NA Diabetes type: 4 Mean age: 63.5 ± NR % Male: 29.05 Longest follow‐up: 7.2 months
Interventions	Control arm: (unrelated lectures) 1) Facilitated relay of clinical information 2) Promotion of self‐management Intervention arm: (community‐based DSME) 1) Facilitated relay of clinical information 2) Patient education 3) Promotion of self‐management
Outcomes	Glycated haemoglobin
Funding source	CMM received support in part from the UCLA Robert Wood Johnson Clinical Scholars Program, the U.S. Department of Veterans Affairs (Grant #67799), the UCLA RCMAR/CHIME under NIH/NIA (P30‐AG021684), and the NIH/NCATS UCLA CTSI (UL1TR000124). OKD received support from a Career Development Award from the NIH/NIA (K08‐AG033630) as well as the Harold Amos Medical Faculty Development Award from the Robert Wood Johnson Foundation. TS was funded by National Center for Global Health and Medicine and Honjo International Scholarship Foundation.
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Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants then were randomly assigned to either the intervention or the control group on an individual basis using sealed envelopes with cards marked either “Study” or “Control”.
Allocation concealment (selection bias)	Unclear risk	Participants then were randomly assigned to either the intervention or the control group on an individual basis using sealed envelopes (opaque?) with cards marked either “Study” or “Control”.
Patient's baseline characteristics (selection bias)	Low risk	Table 1. Baseline characteristics and measurements of participants by group. All patient characteristics have P values above 0.05.
Patient's baseline outcomes (selection bias)	Low risk	Table 1. Baseline characteristics and measurements of participants by group. HbA1c, P = 0.93.
Incomplete outcome data (attrition bias)	High risk	Control group: 257 patients at baseline for HbA1c, 217 at 6 months (15.6% dropouts). Intervention group: 257 patients at baseline for HbA1c, 224 at 6 months (12.8% dropouts). Reasons for dropouts not reported. Approximately 20% of participants in each group dropped out from the study.
Blinding of participants and personnel (performance bias) and of outcome assessors (detection bias)	Low risk	Our outcome of interest is objective (HbA1c).
Selective reporting (reporting bias)	High risk	Retrospectively registered protocol (protocol first posted on December 2005, study started on October 2004). They were supposed to look at the changes in blood pressure, cholesterol and weight (secondary outcomes).
Risk of contamination (other bias)	High risk	Both the control and the intervention arms were exposed to most of the intervention strategies (one‐on‐one sessions to review their laboratory and biometric data, the opportunity to have the study team share their results with their physician, all study participants were given glucose meters and testing strips with a training to use it). However, education about diabetes was given only to the intervention group, including a video and a pictorial workbook.
Other bias	Low risk	No evidence of other bias.