Low-Carbohydrate Diabetes Prevention Program Among Veterans With Prediabetes

The investigators will conduct a single-arm mixed methods pilot study to examine the feasibility and acceptability of a low-carbohydrate diabetes prevention program (LC-DPP). The investigators will estimate weight loss as well as the percentage of participants who achieve 5% body weight loss at 6 month and 12 month timepoints. Weight loss from the pilot VA LC-DPP cohort will be compared to weight loss outcomes from previously published DPP studies and the VA MOVE! program. The investigators will also evaluate secondary outcomes including change in physical activity, mental health, psychosocial functioning, and hemoglobin A1c over the 12-month study period. The investigators will also conduct qualitative interviews with participants at 6 and 12 months.

The Veteran population faces high rates of T2DM with estimates surpassing 20% compared to 14% among the general population. Furthermore, an estimated 25% of overweight or obese Veterans have prediabetes and many will progress to T2DM over time. Fortunately, T2DM can be prevented or delayed through dietary and physical activity changes that promote weight loss of ≥5% body weight. To help Veterans lose weight and avoid obesity-related chronic conditions such as T2DM, the VA Health System offers a lifestyle change program, VA MOVE!. Although MOVE! is widely adopted across the VA Health System, weight loss outcomes are modest (range of 0.13-3.3 kg loss over one year) and less than 20% of participants achieve ≥5% weight loss.

Novel strategies are needed to help more Veterans to lose weight and prevent and manage obesity-related conditions. One promising approach may be through a low-carbohydrate dietary intervention. Consistent with historic United States Dietary Guidelines, diabetes prevention clinical trials and their translational group-based programs, including VA MOVE!, recommend a low-fat, calorie-restricted diet. However, the scientific merit of this recommendation has been criticized. Growing evidence supports the efficacy of low-carbohydrate diets (defined \<26% total energy from carbohydrate per day) and VLCDs (defined as \<10% of total energy from carbohydrate per day) for short-term weight loss, long-term weight maintenance, and improved glycemic control, particularly among individuals with T2DM and insulin resistance.

The objectives of this single-arm mixed methods pilot study are (1) to test the feasibility and acceptability of a low-carbohydrate Diabetes Prevention Program (LC-DPP) among Veterans with prediabetes and (2) to estimate weight loss among LC-DPP participants.

The investigators will recruit approximately 22 patients with body mass index ≥ 25 kg/m2 and prediabetes (defined as hemoglobin A1c \[A1c\] 5.7-6.4%). Participants will be identified by chart review and invited to participate by postal letter. Individuals that do not opt-out of study contact will be screened for eligibility by telephone call. Interested and eligible participants will be invited to attend an in-person information session. During this session, they will receive information about the dietary intervention; written informed consent will be obtained at this time. Study participants will attend a total of 24 group-based classes over the course of 1-year. Body weight will be measured at each session. At 0, 6, and 12-months, the investigators will measure hemoglobin A1c (HbA1c) and cholesterol levels as well as self-reported measures of quality of life, mood, hunger, cravings, and physical symptoms. Primary outcomes will be feasibility (e.g., enrollment, retention) and acceptability (e.g., session attendance, qualitative feedback). Secondary outcomes will change in weight, achievement of ≥5% body weight loss, change in HbA1c, and change in cholesterol levels. During semi-structured interviewed conducted at 6-months and 12-months, the investigators will explore participants' experiences with the program, barriers to and facilitators of adherence to a low-carbohydrate diet, and perspectives on ways to improve the intervention.

Eligibility Criteria:
Inclusion Criteria:

1. Overweight, defined as BMI≥25 kg/m2 \[31\]
2. HbA1c between 5.7-6.4% drawn within 1 year 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.