Comparative Effectiveness of 2 Diabetes Prevention Lifestyle Programs in the Workplace

The City and County of San Francisco Diabetes Prevention Trial

Assiamira Ferrara, MD, PhD; Julia C. McDonald, MS; Susan D. Brown, PhD; Janet G. Alexander, MS; Jennifer L. Christian-Herman, PhD; Stephanie Fisher, MPH; Charles P. Quesenberry, PhD


Prev Chronic Dis. 2020;17(5):E38 

In This Article


To our knowledge, this is among the first studies to evaluate the comparative effectiveness of 2 DPP-derived lifestyle programs recognized by the CDC DPRP and delivered by trained staff from the approved organizations. In this 2-arm, parallel, randomized controlled trial of 158 employees who were at high risk for type 2 diabetes, we found no significant differences in weight loss across 12 months of follow-up between those randomly assigned to receive an in-person lifestyle program delivered at the workplace or an online lifestyle program delivered at participants' convenience. Although we found no significant between-condition differences, both the YMCA-DPP and the VLM-DPP yielded significant reductions in body weight and percentage change in body weight at 6 months. Body weight reductions remained significant at 12 months among participants in the YMCA-DPP but not the VLM-DPP. The YMCA-DPP also resulted in reduced waist circumference at 6 months, although the finding was not significant.

Several DPP-derived lifestyle programs implemented at the workplace have been evaluated using a randomized controlled design; however, most of these interventions were delivered by research staff. In the CCSF trial, we observed a lower percentage of weight loss (from 2.4% to 2.7% at 6 months and 1.6% to 2.5% at 12 months) than that observed in previous randomized controlled trials of lifestyle interventions in workplaces. In a trial conducted at a university worksite in Ohio, participants assigned to a DPP-derived lifestyle intervention had a mean percentage weight change from baseline to 7 months of 5.5%.[22] In a trial at the Pittsburg worksite of the Bayer Corporation, 45% of participants assigned to a DPP-derived intervention lost at least 5% of their body weight.[23] Still, the mean weight loss observed in this trial (ranging from 1.97 to 2.14 kg at 6 months and 1.27 to 2.04 kg at 12 months across intervention conditions) is within the ranges of weight loss observed in other DPP-derived lifestyle interventions implemented at worksites, which have shown short-term weight loss of 0.7 to 5.1 kg at 3 to 6 months and long-term weight loss of 1.43 to 4.9 kg at 7 to 12 months.[9] These trials used a blood test to identify individuals with prediabetes, whereas we used a diabetes risk score. It is possible that the greater weight loss observed in the workplace DPP programs that used blood tests to identify employees at risk for type 2 diabetes was related to higher levels of motivation in participants who received a diagnosis of prediabetes based on laboratory results. Although the magnitude of weight loss observed in this trial was modest, the DPP trial demonstrated that every 1 kg of weight loss resulted in a 16% reduction in type 2 diabetes risk over 3 years.[24,25]

A strength of this study was our ability to randomly assign employees and thereby reduce selection bias. Using the CDC prediabetes screener was also a strength because it allowed nonclinical staff to easily identify employees at risk for type 2 diabetes and invite them to participate. An additional strength was the inclusion of a racially and ethnically diverse population of men and women, particularly given that most trials of technology-based DPP interventions conducted to date have been among primarily white populations.[26] Study limitations include the loss to follow-up; however, we used multiple imputation analyses to compensate for missing data for weight loss and waist circumference. We also observed differences in sex, education, and job type among the employees who were willing versus not willing to be randomly assigned into the study; these differences highlight the need for further research on ways to recruit adults from diverse demographic and socioeconomic backgrounds in preventive lifestyle programs.

In this real-world setting, it was challenging to ensure participant engagement in each intervention program, especially for the online program. Engagement and retention in the program were greater in the YMCA-DPP, where participants were more likely to start the program and completed more sessions than participants in the VLM-DPP. Given the importance of strong engagement to successful program outcomes,[27] these results suggest that offering a program at the worksite during a convenient time for employees, such as during their lunch hour or breaks, may help increase engagement and possibly effectiveness.

Since the conclusion of this trial, the CCSF has begun offering an in-person DPP-derived lifestyle program to all employees at risk for type 2 diabetes. Given the lessons learned from this trial, city officials are prioritizing recruitment and engagement activities as well as the inclusion of settings that employ workers with nonoffice jobs. As evidenced by this study and previous studies,[9,10] worksites offer an opportune setting to reach adults at risk for type 2 diabetes and to offer prevention programs, potentially benefiting employees as well as employers, and potentially reducing future health care costs. CDC has developed a list of elements that should be part of workplace health programs,[28] which offers guidelines for developing and evaluating such programs to increase their effectiveness and sustainability.

In conclusion, both CDC-recognized, worksite-setting lifestyle programs[6] assessed in this intervention yielded weight loss at 6 months. The workplace presents a unique opportunity to offer DPP-derived lifestyle programs.