Mixed methods pilot study of a low-carbohydrate diabetes prevention programme among adults with pre-diabetes in the USA

OBJECTIVES: (1) To estimate weight change from a low-carbohydrate diabetes prevention programme (LC-DPP) and (2) to evaluate the feasibility and acceptability of an LC-DPP. RESEARCH DESIGN: Single-arm, mixed methods (ie, integration of quantitative and qualitative data) pilot study. SETTING: Primary care clinic within a large academic medical centre in the USA. PARTICIPANTS: Adults with pre-diabetes and Body Mass Index of ≥25 kg/m(2). INTERVENTION: We adapted the Centers for Disease Control and Prevention’s National Diabetes Prevention Program (NDPP)—an evidence-based, low-fat dietary intervention—to teach participants to follow a very low-carbohydrate diet (VLCD). Participants attended 23 group-based classes over 1 year. OUTCOME MEASURES: Primary outcome measures were (1) weight change and (2) percentage of participants who achieved ≥5% wt loss. Secondary outcome measures included intervention feasibility and acceptability (eg, attendance and qualitative interview feedback). RESULTS: Our enrolment target was 22. One person dropped out before a baseline weight was obtained; data from 21 individuals were analysed. Mean weight loss in kilogram was 4.3 (SD 4.8) at 6 months and 4.9 (SD 5.8) at 12 months. Mean per cent body weight changes were 4.5 (SD 5.0) at 6 months and 5.2 (SD 6.0) at 12 months; 8/21 individuals (38%) achieved ≥5% wt loss at 12 months. Mean attendance was 10.3/16 weekly sessions and 3.4/7 biweekly or monthly sessions. Among interviewees (n=14), three factors facilitated VLCD adherence: (1) enjoyment of low-carbohydrate foods, (2) diminished hunger and cravings and (3) health benefits beyond weight loss. Three factors hindered VLCD adherence: (1) enjoyment of high-carbohydrate foods, (2) lack of social support and (3) difficulty preplanning meals. CONCLUSIONS: An LC-DPP is feasible, acceptable and may be an effective option to help individuals with pre-diabetes to lose weight. Data from this pilot will be used to plan a fully powered randomised controlled trial of weight loss among NDPP versus LC-DPP participants. TRIAL REGISTRATION NUMBER: NCT03258918.