Patient-centered Goal Setting in the National Diabetes Prevention Program: a Clinical Trial

Diabetes affects 13.0% of US adults, a rising trend that especially impacts racial and ethnic minority and low-income individuals. In response, the Centers for Disease Control and Prevention launched the National Diabetes Prevention Program (NDPP) in 2010 to provide evidence-based lifestyle intervention for adults with risk factors such as overweight/obesity and prediabetes (e.g., A1C 5.7-6.4%). Successes include reaching >300,000 participants and delivery in all 50 states. However, a major concern is limited effectiveness for disadvantaged groups with the highest risk of diabetes. For example, Latinx are the largest ethnic minority group in the US, but least likely to enroll in or complete the yearlong NDPP, which may widen disparities and diminish overall program impact. The NDPP focuses primarily on weight loss to reduce risk, but racial/ethnic minority and low-income groups both lose about half as much weight as white and higher-income groups, respectively (~2% vs. ~4%).

To address these challenges, we adapted the NDPP with an array of personalized goals for risk-reduction to meet individual needs (NDPP-Flex). We developed NDPP-Flex based on the Health Belief Model in which factors like personal characteristics, perceived barriers, and self-efficacy influence health outcomes. We also focused on no-cost modifications per our extensive prior research on NDPP implementation that identified both strengths (e.g., cost-effectiveness) and weaknesses (e.g., low reimbursement rates). We piloted NDPP-Flex with 95 diverse participants (e.g., 76% Latinx) in Federally Qualified Health Centers (FQHCs). We compared outcomes to a demographically matched sample (n=245) from our prior delivery of the standard NDPP with pre-set goals for ≥150 minutes of physical activity per week and ≥5% weight loss. NDPP-Flex participants had similar attendance, physical activity, and weight loss, yet achieved about four times greater A1C improvement (0.22 ± 0.05% vs. 0.06 ± 0.03%; p=.018) and likelihood of normoglycemia at follow-up (OR 4.62; p=.013 [95% CI 1.38-15.50]). Clinically, these outcomes are highly significant as a 0.2% A1C reduction is associated with 58% lower risk of diabetes at 3 years, and a return to normoglycemia predicts 56% lower long-term incidence of diabetes. Our findings were published in Diabetes Care along with an invited commentary which noted that our approach is "innovative" and "should be adopted as part of our national strategy of health promotion."

We propose a cluster-randomized controlled trial of NDPP-Flex versus the standard NDPP to evaluate effects on glycemia, heterogeneity of treatment effects, and mechanisms of change. We will recruit 200 diverse adults with prediabetes (A1C 5.7-6.4%) and normal weight or overweight/obesity. Participants will enroll in classes (N=20) that are randomized to deliver NDPP-Flex or the standard NDPP. The trial is designed to have >95% power to detect anticipated treatment effects of ~0.2% A1C improvement and ~10% increase in participants who reach normoglycemia compared to the control arm. The study will be conducted by an expert team in a health system with the 8th largest network of FQHCs in the US (Denver Health) and in partnership with a premier research institution (University of Colorado). Specific aims are:

Aim 1. To assess effects of NDPP-Flex on A1C change (primary outcome) and achieving normoglycemia (A1C <5.7%) at 12-months (secondary outcome). Hypothesis: Compared to the standard NDPP, NDPP-Flex will reduce A1C and increase the likelihood of normoglycemia.

Aim 2. To assess heterogeneity of treatment effects on A1C by demographic characteristics (age, gender, race/ethnicity, income, language) and for individuals of normal weight (vs. overweight/obesity) to understand for whom NDPP-Flex may be effective. Hypothesis: For all subgroups of participants, NDPP-Flex will result in equivalent or superior A1C improvement than the standard NDPP.