Foster 2013.

Study characteristics
Methods	A randomized comparison of a commercially available portion‐controlled weight‐loss intervention with a diabetes self‐management education program RCT (NA clusters and NA providers), conducted in 1) Patients recruited and treated at 2 medical centres in Philadelphia. 2) Sessions led by experienced practitioners (that is, lifestyle interventionists or certified diabetes educators, as appropriate). In United States of America. 2 arms: 1. Control (diabetes self‐management education‐DSME) (control arm) and 2. Intervention (group lifestyle intervention with portion‐controlled diet‐PCD) (intervention arm)
Participants	Control arm N: 50 Intervention arm N: 50, NA, NA Diabetes type: 2 Mean age: 55.6 ± 9.53 % Male: 41 Longest follow‐up: 6 months
Interventions	Control arm: (diabetes self‐management education ‐ DSME) 1) Case management 2) Patient education 3) Promotion of self‐management 4) Continuous quality improvement Intervention arm: (group lifestyle intervention with portion‐controlled diet ‐ PCD) 1) Case management 2) Patient education 3) Promotion of self‐management 4) Continuous quality improvement
Outcomes	Glycated haemoglobin Systolic blood pressure Diastolic blood pressure Low‐density lipoprotein
Funding source	This trial was supported by research grants from Nutrisystem, Inc. to Temple University and the University of Pennsylvania. This study was also supported by LifeScan, Inc.
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomly assigned within site (stratified for insulin use), via a random‐number generator.
Allocation concealment (selection bias)	Unclear risk	Not reported. The study statistician generated the random allocation sequence, and research co‐ordinators enrolled participants and randomly assigned them to treatment conditions.
Patient's baseline characteristics (selection bias)	Low risk	Table 1. Legends: There were no significant differences between the 2 groups. The 2 treatment conditions did not differ significantly on any baseline characteristics (as shown in Table 1).
Patient's baseline outcomes (selection bias)	Low risk	Table 1. Legends: There were no significant differences between the 2 groups. The 2 treatment conditions did not differ significantly on any baseline characteristics (as shown in Table 1).
Incomplete outcome data (attrition bias)	Low risk	Only one lost to follow‐up in the intervention arm out of 100 (1%).
Blinding of participants and personnel (performance bias) and of outcome assessors (detection bias)	Low risk	All objective outcomes (HbA1c, SBP, DBP and LDL).
Selective reporting (reporting bias)	High risk	Retrospectively registered protocol (protocol first posted in December 2010, study started in March 2010, 6 months intervention). The authors only mention weight and HbA1c as outcomes, but the paper also reports blood pressure and LDL. The outcomes should have been reported for 0, 3 and 6 months time frame, but they were only reported at baseline and 6 months.
Risk of contamination (other bias)	Unclear risk	Both study conditions offered a stronger behavioural intervention than what most patients with type 2 diabetes are likely to receive in practice. Lifestyle intervention included the use of a prepackaged, portion‐controlled diet (PCD, Nutrisystem D, Fort Washington, PA, USA). Control sessions, led by a certified diabetes educator, were conducted in a format similar to the PCD intervention group, beginning with a review of the prior session’s readings and homework and followed by the introduction of a new topic. Control participants were instructed to consume a balanced deficit diet. Participants in both treatment conditions attended group sessions (at weeks 0, 1, 2, 4, 8, 12, 16, 20 and 24). All participants were instructed to monitor and record their blood glucose. All records were reviewed by study staff at each session.
Other bias	Low risk	None identified.