A systematic review of real-world diabetes prevention programs: learnings from the last 15 years

Background The evidence base for the prevention of type 2 diabetes mellitus (T2DM) has progressed rapidly from efficacy trials to real-world translational studies and practical implementation trials over the last 15 years. However, evidence for the effective implementation and translation of diabetes programs and their population impact needs to be established in ways that are different from measuring program effectiveness. We report the findings of a systematic review that focuses on identifying the critical success factors for implementing diabetes prevention programs in real-world settings. Methods A systematic review of programs aimed at diabetes prevention was undertaken in order to evaluate their outcomes using the penetration, implementation, participation, and effectiveness (PIPE) impact metric. A search for relevant articles was carried out using PubMed (March 2015) and Web of Science, MEDLINE, CENTRAL, and EMBASE. A quality coding system was developed and included studies were rated independently by three researchers. Results Thirty eight studies were included in the review. Almost all (92 %) provided details on participation; however, only 18 % reported the coverage of their target population (penetration). Program intensity or implementation—as measured by frequency of contacts during first year and intervention duration—was identified in all of the reported studies, and 84 % of the studies also reported implementation fidelity; however, only 18 % of studies employed quality assurance measures to assess the extent to which the program was delivered as planned. Sixteen and 26 % of studies reported ‘highly’ or ‘moderately’ positive changes (effectiveness) respectively, based on weight loss. Six (16 %) studies reported ‘high’ diabetes risk reduction but ‘low’ to ‘moderate’ weight loss only. Conclusion Our findings identify that program intensity plays a major role in weight loss outcomes. However, programs that have high uptake—both in terms of good coverage of invitees and their willingness to accept the invitation—can still have considerable impact in lowering diabetes risk in a population, even with a low intensity intervention that only leads to low or moderate weight loss. From a public health perspective, this is an important finding, especially for resource constrained settings. More use of the PIPE framework components will facilitate increased uptake of T2DM prevention programs around the world. Electronic supplementary material The online version of this article (doi:10.1186/s13012-015-0354-6) contains supplementary material, which is available to authorized users.

High-risk adult members of the church were identified using the 7-question DRA tool. Two weeks prior to implementing the DRA, weekly announcements were placed in the Sunday bulletin detailing the dates of the DRA. The DRA was performed during 2 successive Sunday services...The DRA was distributed to every adult congregant, collected on the same day… Gilis-Januszewska et. al. 2011 [76] DE-PLAN Poland NAC Not Reported Study population is 'Adults at risk of diabetes. 'Advertisements were placed alongside 800 self-screening questionnaires in the GP's waiting rooms. In addition, those patients with known risk factors were approached by nursing and medical staff. Katula et. al. 2011 [77] HELP PD NAC Not Reported Study population Adults with prediabetes. "Standard recruitment strategies were employed, including mass mailing at targeted addresses, direct provider referral, and community events." Between 500-2000 mailings per week (over 24-mo recruitment period) but total N not reported. Kumanyika et. al. 2011 [48] Think Health! NAC Not Reported Study participants identified from billing lists and clinician referrals. Local university-or hospital-affiliated primary care practices, as well as independent individual or group physician practices. All clinical sites were asked to commit to recruiting at least 50 participants. Number of sites not reported.

NAC Not Reported
All general practitioners in the four nearest municipalities to the hospital were each supplied with ten FINDRISC-questionnaires by post, asked to use them on patients at risk for T2D and were requested to refer individuals aged 18-64 with a FINDRISC-score > 9 to the hospital.
Penn et. al. 2011 [43] NLNY NAC Not Reported The town of Middlesbrough was chosen for the pilot because of the large proportion of the target population and high prevalence of T2D. Target population not reported. Social marketing campaign attracted 271 individuals. Ruggiero et. al. 2011 [78] HLP NAC Not Reported Study population Adults at risk of diabetes. The participants were recruited during free health screenings (n = 1162 people were assessed at 20 study-sponsored screenings) held in the community at various locations incl. public schools, community/ family service centres, a hospital, and health centres. Posters and flyers were delivered to schools, community centres and local businesses.

Penetration Author Year Study ID Scoring Target Population Description
Sakane et. al. 2011 [79] Japanese Study NAC 10000+ Study population Individuals with impaired glucose tolerance. Using the data from health check-ups, those who met the eligibility criteria were extracted. It was roughly estimated that there were more than 10,000 people with borderline hyperglycemia at the 32 collaborative centres. Each centre recruited study candidates using posters, through flyers, and by word of mouth during the time period of the study. Study population Adults at risk of diabetes and/or CVD. A total of 8193 men and women aged 30-50 years living in several municipalities were invited to participate in a selective screening procedure by mail. The target group was approached after identification of date of birth and absence of diabetes and known CVD from 12 participating general practices.
The target population in the protocol paper was 12,000. 8,193 men and women aged 30 to 50 years living in several municipalities in a semirural region (West-Friesland) of the Netherlands were invited to participate in a selective screening procedure by mail. The primary recruitment outreach method entailed drawing from the GLFHC patient panel by identifying potentially eligible patients who received a mail letter of invitation… Additional outreach methods included announcements on local radio and television stations, newspaper advertisements, and mailings to non-GLFHC physicians. Patients were also screened as walk-ins if they learned of a screening event via word-ofmouth or community outreach.
Piatt et. al. 2012 [81] GLB ( [82] SDPI-DP NAC Not Reported SDPI-DP identified potential participants (n = 18,134) mainly through community events such as health fairs but also recruited participants from local clinics or by provider referral.

Penetration
Author Year Study ID Scoring Target Population Description Ma J et. al. 2013 [38] E-LITE High 3439 Study population overweight / Obese adults with increased cardio-metabolic risk. "We identified overweight or obese, at-risk adults receiving care from the 21 active primary care providers at the study clinic site using the electronic health record system.  [47] Prevent NAC Not Reported Participants were recruited from online advertisements, seeking individuals with a selfreported clinical diagnosis of pre-diabetes occurring within the past year. Zyriax et. al. 2014 [34] DELIGHT High 3000 ALL (n = 3000) employees from five companies were approached through flyers, intranet, or works meeting to invite for further check-up if their waist circumference was above certain limit. 3000/3000 = 1 (100%) Savas et. al. 2015 [44] IGT Care Call NAC Not Reported Seven GP practices with IGT registers participated in the project. They referred people with IGT diagnosed by a 2-hour oral glucose tolerance test.

Note: NAC = Not Able to Calculate
Supplementary Frequency: 5 sessions of at least 60 minutes covering diet, exercise, and behavior modifications were held, the first was a one-to-one meeting and was followed by group sessions based on behavioral counseling and focusing on practical lifestyle tips. 5/22=22.7% Duration: 5 sessions of at least 60 minutes covering diet, exercise, and behavior modifications were held. > 12-months Fidelity: To minimize the potential lack of fidelity, the professional health care providers (n=8) were assigned to the sessions in a quasirandomized mode (i.e., a scheduled rotation of experts among sessions to assure a balanced intervention for all subjects), and the delivered information was controlled. Each provider checked messages previously given and patients' expectations. The sessions had a flexible structure, sensitive to cultural differences and patient expectations, that combined a structured core (common topics, recommendations, and educational leaflets) with flexibility in verbal presentation tailored to requirements and retention capacity. DPP (churchbased)

Low Low Moderate
Frequency: A six-session program was designed from the 16-session intensive lifestyle arm of the DPP. The six sessions were presented over a seven-week period following a schedule determined by the participants. Advance letters were mailed to remind the participants of each upcoming session and to encourage them to meet the goals of the previous session. Participants were supported with calls, letters and reminders of sessions. Number of advance letters and calls not specified. 6/22 = 27.3% Duration: Seven-week period Fidelity: The research team selected six of the NIH-DPP's 16 sessions for this pilot study based on information from prior focus groups with church members. The 16-session DPP has three themes: nutrition, physical activity and behaviour change. Each theme is the main focus of four sessions. We identified two sessions from each of these three categories to make up the six sessions. The material was modified to be used in a church-based group setting from its original design for individual use with a lifestyle coach. A nurse educator and physician performed the modification, adapting the information to a group setting. Each session was led by volunteer healthcare professionals. The session leaders attended a 60-minute training session led by the research team on how to present the lifestyle balance curriculum to the church community.

DEPLOY High High High
Frequency: The intervention core curriculum involved 16 classroom-style meetings. Program sessions lasted 60-90 minutes, and the entire core curriculum was delivered over 16-20 weeks. …maintenance activities following the core curriculum sessions involved monthly, large-group meetings. 22/22=100% Duration: >12-months Fidelity: The study was based on the US-DPP model. Several approaches were used to ensure that intervention sessions were delivered with fidelity to the DPP model. These approaches were based on similar strategies used during the DPP, and were developed by a training core of DPP project staff, YMCA personnel, and the principal investigator. Quality assurance began with the structured training and certification process described above, adapted from the DPP manual of operations.

Frequency:
The intervention included a 6-week group self-management education program, a gymnasium-based or home-based 12-week resistance training program, and a 34-week maintenance program. During week 1 -6, the intervention included six 1.5 hours group self-management education program. During weeks 7-18, participants were assigned to either a gym-based or a home-based 12week resistance training program. The intervention included a 34-week maintenance program. Participants were encouraged to continue the recommended regimen and to attend three 2-hour group reinforcement sessions.
(3 * 2 = 6 hours) and (6 / 1.5 = 4 sessions) They were also sent two newsletters containing self-management, healthy eating, and physical activity advice. Frequency: The 1-year intervention programme consisted of six sessions (1 hour each) held by a registered dietitian at the area of the participants' residence or work. Groups of 6-10 persons were constructed. 6/22=27.3% Duration: 12 months Fidelity: According to the general DE-PLAN protocol, each centre of the participating countries was allowed to follow any intervention strategy-assisted self-managed, groupbased or individual-based consultation-with the objective of achieving better understanding of the disease risk from the participants and of building up motivation for an intention to change lifestyle. In our study, group-based consultation interventions were chosen, as they were deemed to be more conveniently implemented, more cost-effective and efficacious from the participants' standpoint.

Low Moderate
Frequency: This pilot study was carried out in a total of 5 churches. Two group-based programs, a 6-session program and a 16-session program, were developed. Two churches participated in the 6-session diabetes prevention program and 3 churches participated in the 16-session program. 6/22=27.3% 16/22=72.7% Duration: < 6-months Fidelity: The intervention used in this study was modeled after the lifestyle intervention arm of the NIH-DPP… The team modified the lifestyle balance curriculum of the DPP from an individual based design to a group-based design that is culturally appropriate for implementation in an African American church setting… The new format was test piloted in a small group setting using a research team that included African American members of local churches. Minor modifications were made based on feedback from church participants who completed the program. Frequency: Participants met weekly for CHW-led group sessions during the first 6 months. Participants also received three personalized consultations with a registered dietician (during months 1, 3, and 6). During months 7-12, participants received two scheduled contacts with the CHW each month, one group session and one telephone contact. 26 weekly sessions + 3 personalized consultations + 3.5 schedule contacts each months for 6 months (3.5 * 6 = 21) = 50 sessions  50/22=227% Duration: > 12 months Fidelity: The HELP PD project was designed to translate the methods of the DPP into the community via key modifications to enhance feasibility and dissemination.. Intervention content standardization was supported by a DVD series developed by the research team. The 16 core DPP sessions were modified based on a prior DPP adaptation. Some DPP core content was put in supplemental handouts, and some was shifted to the maintenance period in the second year of treatment. The amount of content conveyed per session was reduced to a set of key points that could be summarized in a two-page handout. These handouts were packaged in participant manuals, which also included a CD with audio narration of the first 12 sessions… The year 1 treatment protocol was implemented as intended, although not all treatment visits were completed with all patients due to nonattendance. ...we do not have data on time spent in counseling or quality of PCP or LC counselling provided. We also cannot assess possible differences in how PCPs counseled participants in Basic vs. Basic Plus (based on their inadvertent knowledge of the participant's randomization assignment) and do not know the degree of individual tailoring that occurred within counseling sessions. Although materials were standardized, PCPs were encouraged to use their own styles of working with patients generally and with the particular patient. Frequency: NLNY trainers delivered a 10-week programme of twice weekly 1.5 h sessions to groups of 15-20 participants. Each NLNY session comprised a supervised PA or, on two or three occasions within each 10-week programme, a cookery session, followed by a reflective discussion that covered PA, nutrition, weight management and strategies for behaviour change. Monthly NLNY newsletters with information, advice and recipes were available to participants, mostly online. At the end of the 10-week programme, participants who had completed ≥80% attendance received an 'access to leisure' card that enabled free leisure service use for 12 months. After the programme, ongoing support with regular mobile phone text message and email reminders, 'drop-in' activity sessions and encouragement to join in local events such as organised walks and runs continued up to the assessment at 12 months of follow-up. 10 * 2 = 20 sessions + mobile phone, text messages and email reminders; drop-in activity sessions etc. Frequency: During the initial six months, 4 group sessions were conducted with each session lasting 2 or 3 hours. The individual session was conducted biannually during the three years with each session lasting 20 to 40 minutes. To reinforce the intervention, between-visit contact by fax was also made monthly during the initial twelve months. 4 group sessions; 2 individual sessions; and 12 monthly contacts through fax = (6 * 0.25 = 1.5 sessions) 4 + 2 + 1.5 = 7.5 / 22 = 34% Duration: > 12 months Fidelity: Compared with the DPS and DPP, the present study had a less intensive intervention. The majority of the public health nurses, reflecting the real world primary healthcare setting, did not have special training in lifestyle modifications. At a feasible level, they carried out the intervention using the protocol and educational materials provided by the study group. As a rule, the same study nurse carried out the interventions on the same participant during the study. But this was not always possible due to a personnel change at the collaborative center.

Frequency:
The intervention consisted of two steps (initial and further reinforcement). The intensive intervention consisted of a six-hour educational program (divided in 2 to 4 sessions) to be performed either individually or in small groups (5 to 15 people). Participants were reminded (telephone call) about the date and hour of their next group session to ensure compliance, and every 6-week (minimum) they were contacted (also by telephone Frequency: It was delivered in Spanish and English and consisted of a 6-month active intervention phase and a 6-month maintenance phase. 1 introductory session; 1 in-person planning session; 12 telephone counseling calls. 1 + 1 + 6 (12 telephone calls * 0.5) = 8/22 = 36% Duration: 12 months Fidelity: Not clear in the article, however, the project's internet site mentions about a standard curriculum consisting of materials for program users and participants.

Moderate Moderate High
Frequency: Six individual 30-minute counselling sessions, followed by 3-monthly booster sessions by phone for a period of one year. 6 + 1.5 (3 telephone sessions * 0.5) = 7.5/22 = 34.09% Duration: 12 months Fidelity: We assessed the extent to which the various intervention components were delivered as intended. The counselling sessions were tape-recorded to allow assessment of the validity of MI and PST provided by the practice nurses. Two tape-recorded sessions of ≥ 15 minutes from all practice nurses were drawn at random using a computerized randomization program and transcripts were made; all final samples were then independently analyzed by two researchers. Because not all samples contained sessions in which PST was used, 10 extra random sessions have been independently analyzed using the PSCC.
Ockene et. al. 2012 [80] LLDPP High Moderate Moderate Frequency: Three individual and 13 group sessions over a 12-month period. 16/22=72.7% Duration: 12 months Fidelity: Intervention fidelity was facilitated through extensive training in the delivery of the intervention protocol, including the nutritional & exercise aspects of the intervention, the theoretical background, and training in motivational counselling and group management skills.

Moderate Moderate
Frequency: Twelve weekly sessions over 12-14 weeks (lasted ~90 min) in the groups of 5 to 13 participants. 12/22=54.5% Duration: 12 months Fidelity: The DPP lifestyle intervention was adapted to a 12-session group-based program.

Frequency:
The curriculum was delivered in group settings within 16-24 weeks after baseline assessment and typically was taught by the program dietitian and/or health educator. It was supplemented by monthly individual lifestyle coaching sessions to individualize goals and plan and to identify and solve barriers to participation. 22/22=100% Duration: 12 months Fidelity: Based on the DPP lifestyle intervention.

Implementation Author
Year Study ID Frequency Duration Fidelity Description Ma J et. al. 2013 [38] E-LITE High High High Frequency: E-LITE was a 3-arm, primary care-based randomized trial designed to evaluate the effectiveness of 2 adapted DPP lifestyle interventions: (1) a coach-led, face-to-face group intervention and (2) a self-directed DVD intervention. Participants in both intervention groups completed a 3-month intensive intervention phase and a 12-month maintenance phase. During the intensive intervention phase, participants received an adapted, 12-session DPP lifestyle intervention curriculum. The curriculum was delivered face-to-face in 12-weekly classes to coach-led intervention participants or via a home-based DVD to self-directed intervention participants. Coach-led intervention participants had food tastings at check-in and 30 to 45 minutes of guided physical activity at the end of each weekly class.
[Twelve weekly group sessions (1.5 -2hrs each) in the first 3 months. From month 4-15, contact every 2-4 week depending on participant needs and preferences. Individual, secure email/phone contacts with personalized progress feedback and lifestyle coaching through the maintenance phase (mo4-15).] Duration: > 12 months Fidelity: To assure intervention fidelity, the DPSC provides training and certification of instructors who will be delivering the intervention to patients. The E-LITE dietitian lifestyle coach completed this DPSC instructor certification. During group sessions, the DPSC groupbased DPP intervention manual was followed, with the only exceptions being two additional activities added to all group sessions: a food-tasting at check-in and a 30-to 45-min physical activity demonstration and practice at the session end. Duijzer et. al. 2014 [49] SLIMMER Low Moderate Moderate Frequency: A dietician gave tailored dietary advice during six individual consultations within the 10-month intervention period (30-60 min per consultation; in total 4 h per participant). In addition, the dietician organised one group session. The physical activity intervention consisted of a combined aerobic and resistance exercise programme (proportion 2:1) at the physiotherapist's practice. Weekly training sessions with a duration of 1 h were group-based and supervised by a skilled physiotherapist. Subjects had free access to the training sessions and were stimulated to participate for at least 1 h per week. 6 + 1 session = 7/22 = 31.8% Low Duration: 10 months Fidelity: The SLIMMER intervention resembles the SLIM intervention, which was based on the Finnish Diabetes Prevention Study. Overall, the intervention was implemented as planned. Some parts of the protocol, however, were omitted or adjusted by health care professionals. This mostly concerned measurements and planning aspects regarding intervention elements.

Implementation Author
Year Study ID Frequency Duration Fidelity Description Sepah et. al. 2014 [47] Prevent Moderate High Moderate Frequency: The DPP curriculum was presented in an asynchronous online format that resembled popular online learning platforms such as Coursera. The Prevent program began with a 16-week core program phase, consisting of 16 online weekly lessons adapted from the CDC National DPP core curriculum. Once participants completed the 16-week core phase, they were invited to participate in the post-core phase, totalling 12 months. The post-core phase included 9 monthly lessons from the CDC National DPP post-core curriculum. The post-core phase differed in that all groups were combined into a larger participant-led "super-group" and focused on maintaining lifestyle habits and weight loss achieved during the core program. 16 + 9 = 25 (online sessions = 25 * 0.5 sessions = 12.5 sessions) 12. The exclusion of the subjects, who refused to participate, did not seem to affect results because they were wellbalanced between both groups. Moreover, the sensitivity analysis based on the intent-to-treat population confirmed the results based on participants only. After 12 months, weight loss was significantly higher in PREDIAS (-3.8kg) (4.1%) than in the control group (-1.4kg).
An intention-to-treat analysis was performed using the baseline observation carried forward method. Statistical analyses were performed by paired t tests for within-group differences and independent t tests for between-group differences Penn et. al.
2009 [70] EDIPS-Newcastle NAC Low High At 12-months, mean weight change in intervention group was -2.3 kg vs. 0.01 kg in the control group. The absolute incidence of T2D was 32.7 per 1000 person-years in the intervention group and 67.1 in the control group. The overall incidence of diabetes was reduced by 55% in the intervention group.