Diabetes prevention at the national level
The Healthy Living Partnerships to Prevent Diabetes Study: 2-Year Outcomes of a Randomized Controlled Trial

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Background

Since the Diabetes Prevention Project (DPP) demonstrated that lifestyle weight-loss interventions can reduce the incidence of diabetes by 58%, several studies have translated the DPP methods to public health−friendly contexts. Although these studies have demonstrated short-term effects, no study to date has examined the impact of a translated DPP intervention on blood glucose and adiposity beyond 12 months of follow-up.

Purpose

To examine the impact of a 24-month, community-based diabetes prevention program on fasting blood glucose, insulin, insulin resistance as well as body weight, waist circumference, and BMI in the second year of follow-up.

Design

An RCT comparing a 24-month lifestyle weight-loss program (LWL) to an enhanced usual care condition (UCC) in participants with prediabetes (fasting blood glucose=95−125 mg/dL). Data were collected in 2007−2011; analyses were conducted in 2011−2012.

Setting/participants

301 participants with prediabetes were randomized; 261 completed the study. The intervention was held in community-based sites.

Intervention

The LWL program was led by community health workers and sought to induce 7% weight loss at 6 months that would be maintained over time through decreased caloric intake and increased physical activity. The UCC received two visits with a registered dietitian and a monthly newsletter.

Main outcome measures

The main measures were fasting blood glucose, insulin, insulin resistance, body weight, waist circumference, and BMI.

Results

Intent-to-treat analyses of between-group differences in the average of 18- and 24-month measures of outcomes (controlling for baseline values) revealed that the LWL participants experienced greater decreases in fasting glucose (−4.35 mg/dL); insulin (−3.01 μU/ml); insulin resistance (−0.97); body weight (−4.19 kg); waist circumference (−3.23 cm); and BMI (−1.40), all p-values <0.01.

Conclusions

A diabetes prevention program administered through an existing community-based system and delivered by community health workers is effective at inducing significant long-term reductions in metabolic indicators and adiposity.

Trial registration

This study is registered at Clinicaltrials.gov NCT00631345.

Introduction

Latest estimates indicate that almost 26 million people in the U.S. have diabetes (8.3% of the population), and another 79 million adults have prediabetes.1 Although diabetes-related mortality has decreased by 8.3% over the past 10 years, the prevalence of diabetes has increased and is accompanied by greater prevalence of complications (e.g., cardiovascular disease, renal disease, lower extremity dysfunction).2 Thus, despite improved treatment of diabetes, its overall public health burden continues to increase and highlights the critical importance of prevention.3 International clinical trials, including the Diabetes Prevention Program (DPP)4 and the Finnish Diabetes Prevention Study (FDPS),5 have demonstrated that lifestyle weight-loss programs can prevent the incidence of diabetes in individuals with elevated blood glucose by up to 58%. Because these studies involved substantial amounts of resources and specialized personnel, several studies have attempted to translate these programs to more public health−friendly contexts to lower costs and increase access.

Two recent reviews6, 7 have examined critically several diabetes prevention translational studies. Although the studies reviewed overlap substantially, the analyses each take individual approaches to examining the literature and reach contrasting conclusions. Whittemore7 reviewed 16 studies that translated the DPP lifestyle weight-loss intervention and categorized each according to the study context: (1) hospital outpatient; (2) primary care; (3) community; and (4) work and church settings. Of the studies reviewed, 81% (n=13) were one-group designs; the length of follow-up ranged from 3 months to 2 years; and weight loss at the longest point of follow-up varied between −1.0 kg and −8.6 kg.

Each study was reviewed critically using the RE-AIM8 framework (reach, effectiveness, adoption, implementation and maintenance). From this review, the authors concluded that (1) the studies varied considerably in terms of the five framework elements; (2) hospital outpatient diabetes education models of care were particularly efficacious at inducing weight loss; and (3) reach and efficacy appear to have an inverse relationship. That is, the settings with the greatest ability to reach diverse samples, such as community and work/church settings, demonstrated the least weight loss and more-restricted settings such as hospital practices demonstrated the greatest weight loss.

Ali and colleagues6 conducted a meta-analysis on 28 studies that tested various translational models for disseminating the methods of the DPP. Of the 28 studies reviewed, four were RCTs, two were cluster-RCTs, 20 were single-group pre−post studies, and two were nonrandomized controlled studies. The authors classified studies based on the type of personnel used to deliver the program: medical and allied health professionals, lay community members, and electronic media−assisted methods. They found that each group of studies demonstrated significant weight loss at 12 months of follow-up: medical and allied health professionals, −4.27 kg; lay community members, −3.15 kg; electronic media−assisted, −4.20 kg; overall mean = −3.99 kg. Based on sensitivity analyses, the authors concluded that programs led by lay community members may have been associated with better weight loss than that achieved by medical and allied health professionals.

A recent analysis of six DPP translational studies that utilized community health workers (CHWs)9 supports the conclusions of Ali and colleagues.8 The authors adopted the definition of CHWs that was developed by the DHHS, Health Services and Resources Administration: lay community members that work in association with local healthcare providers in a variety of settings and share a common culture (i.e., ethnicity, SES, language, life experience) with the individuals they serve.10 Of the six studies reviewed, two were RCTs, one was a cluster RCT, and three were single-group designs. Two studies included follow-up of 12 months and four included follow-up ranging from 3 to 6 months. All studies demonstrated significant weight loss, ranging from −1.5 kg (12 weeks of follow-up) to −7.27 kg (12 months of follow-up).

The manner in which CHWs were utilized varied considerably among studies. In one study, CHWs supported a team of dietitians and exercise specialists.11 Trained YMCA staff delivered a group-based DPP lifestyle weight-loss program in the DEPLOY (delivery of a group-based DPP lifestyle intervention offered at the YMCA) study.12 However, in several studies, the CHWs delivered group-based DPP lifestyle interventions.13, 14, 15, 16 Despite the variability in efficacy and the manner in which CHWs are used among the studies reviewed, this approach appears to hold great promise for translating the DPP lifestyle weight-loss intervention.

Taken together, the literature suggests that a number of distinct approaches for translating the DPP lifestyle weight-loss intervention appear to be feasible and efficacious. However, this body of literature is dominated by single-group designs; a large number of the studies reviewed include pilot studies with small samples, and short-term follow-up; and only one study13 reported significant intervention effects on glucose. The Healthy Living Partnerships to Prevent Diabetes (HELP PD)13, 17 was an RCT that translated the DPP lifestyle intervention through a partnership between an existing community system and CHWs. The intervention was administered through a local diabetes care center by registered dietitians (RDs) and delivered by CHWs in community settings. At 12 months of follow-up, participants in the lifestyle weight-loss intervention experienced significantly greater reductions in body weight, waist circumference, BMI, glucose, insulin, and insulin resistance as compared to an enhanced usual care comparison group.13

The HELP PD study is also the only DPP translational study to report significant changes in fasting blood glucose (−4.3 mg/dL during the first year, p<0.001).13 Although the results of HELP PD and other DPP translational studies are promising, the long-term effectiveness (beyond 12 months) of these approaches remains to be determined. Therefore, the purpose of the present study is to report the impact of the HELP PD approach during the second year of follow-up on fasting blood glucose, insulin, insulin resistance, body weight, waist circumference, and BMI.

Section snippets

Study Design

The design and methods of the present study have been reported elsewhere.13, 17 Briefly, this RCT sought to translate the DPP lifestyle weight-loss intervention through a local diabetes education program (DEP) and CHWs. Overweight and obese volunteers with elevated fasting blood glucose were assigned randomly to either a group-based, DPP lifestyle weight-loss (LWL) intervention or an enhanced usual care comparison condition (UCC).17 The primary outcome was fasting blood glucose, and other

Results

A total of 301 overweight or obese participants with elevated fasting blood glucose were randomized. Figure 1 illustrates the recruiting, screening, randomization, and retention process. The participants who were randomized into the study represented the racial composition of the population of Forsyth County, North Carolina, where the study was conducted. The group was well educated with a mean age of 57.9 (SD=9.5) years. The average BMI was in the obese range (32.7, SD=4.0), and the average

Discussion

The purpose of this study was to examine the impact of the HELP PD intervention on fasting blood glucose, insulin, insulin resistance, and adiposity in the second year of follow-up. Results indicate that the significant reductions in body weight, BMI, waist circumference, fasting blood glucose, insulin, and insulin resistance achieved during the first year of the program largely were maintained in the second year as compared to the enhanced usual care condition. Additionally, at 24 months, the

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