A Low-Carbohydrate Diabetes Prevention Program

The investigators will conduct a single-arm mixed methods pilot study to estimate weight loss as well as the percentage of participants who achieve 5% weight loss in a 16-week, Low-Carbohydrate Diabetes Prevention Program (LC-DPP). Weight loss from the pilot LC-DPP cohort will be compared to weight loss outcomes from previously published DPP studies. The investigators will also evaluate secondary outcomes including change in physical activity, mental health, psychosocial functioning, and hemoglobin A1c over the 6-month study period.

An estimated 86 million US adults are have prediabetes, and, without intervention, many will develop T2DM over time. Fortunately, T2DM can be prevented or delayed through modest lifestyle changes. The landmark Diabetes Prevention Program (DPP) Trial demonstrated a 58 percent reduction in the 3-year incidence of T2DM among individuals with prediabetes who achieved 7 percent body weight loss and engaged in routine physical activity. Accordingly, the DPP lifestyle intervention has been translated to communities across the United States, and, on average, participant weight change is 4 percent at 12 months. Thus, while group-based DPPs and can effectively promote weight loss among some participants, many DPP participants do not achieve the program goal of 5 to 7 percent body weight loss.

Novel strategies to help participants achieve DPP weight-loss goals are important for two key reasons. First, weight loss is the primary driver of T2DM risk reduction, and the potential population health impact of the intervention is diminished when participants do not lose weight. Second, a growing number of health plans including Medicare offer coverage for the DPP and proposed reimbursement is largely tied to weight loss of at least 5 percent at 6 months and 12 months. The DPP costs approximately $400-$500 per participant per year. Unfortunately, organizations that offer the DPP may be reimbursed for much less than this if participants do not meet weight loss goals, which could significantly compromise the program's long-term financial sustainability.

One promising approach to help DPP participants lose more weight may be through a low-carbohydrate (LC) dietary intervention. Consistent with United States Dietary Guidelines (USDG), the original DPP Trial and translational group-based curricula recommend a low-fat (LF), calorie-restricted diet. However, there is growing controversy regarding the scientific merit of the Dietary Guidelines as well as growing recognition that LC diets may be more effective than LF diets for short-term weight loss and long-term weight maintenance. Notably, weight loss occurs without calorie restriction and LC diets improve blood glucose levels among individuals with T2DM and insulin resistance. Thus, a LC dietary intervention for prediabetes may augment individual weight loss and T2DM risk reduction while also maximizing third-party reimbursement.

The aim of this mixed methods pilot study is to test whether a LC-DPP may lead to greater weight loss than the original DPP. In addition to objective measures of this program's preliminary efficacy (e.g. weight, HbA1c) the study team will also obtain qualitative participant feedback on the intervention. Taken together, these data will be used to improve the curriculum and inform a larger-scale intervention.

Eligibility Criteria:
Inclusion criteria:

1. Overweight, defined as BMI≥25 kg/m2 \[31\]
2. HbA1c between 5.7-6.4% drawn within 6 months of the study start date
3. Willingness to participate in group-based classes
4. Able to engage in at least light physical activities such as walking.

Exclusion criteria:

1. History of type 1 diabetes or type 2 diabetes
2. Current participation in another lifestyle or behavior change program or research study
3. Vegetarian or vegan lifestyle
4. History of bariatric surgery
5. Inability to read, write, or speak English
6. Inability to provide informed consent
7. Women who are pregnant or intend to become pregnant during the intervention period.
8. Insured by Premier Care or Grad Care; these individuals have the opportunity to participate in a standard DPP, which is offered as a covered benefit through their health plan.