BACKGROUND/OBJECTIVES: Traditional diet management for type 2 diabetes (T2DM) is often complex and effortful to sustain. Nudging offers low-effort and automatic approaches to dietary behaviour change yet remains underexplored in T2DM. This study evaluated the independent and combined 6-month effects of nudging education (NE) and nudging tableware (NT) on HbA1c, along with other secondary health outcomes, among adults with T2DM and overweight/obesity, compared to their non-nudge counterparts (control education, CE; control tableware, CT).

METHODS

A 2 × 2 factorial cluster RCT was conducted in 12 primary healthcare settings in China (pre-registered as ChiCtr2100044471). Participants were randomly assigned to the nudging education group (NE + CT), the nudging tableware group (CE + NT), the combined group (NE + NT) or the full-control group (CE + CT) for 1 month. The primary outcome was HbA1c. Secondary outcomes included dietary behaviours, metabolic indicators, and psychological health. Generalized linear mixed models were used for analysis.

RESULTS

A total of 284 participants (mean age, 52.28 years; 54.3% male) were randomly assigned and included in the analysis. After 6 months, NE and NT independently led to HbA1c reductions (-0.76%, < 0.001; -0.33%, = 0.042, vs. controls), with an additive but non-interactive effect when combined, resulting in a 1.04% reduction ( < 0.001) in the combined group. They also improved total calorie, macronutrient, and vegetable intake, FBG, plasma lipids, and BMI. NE additionally reduced diabetes distress and enhanced self-efficacy.

CONCLUSIONS

Both NE and NT improved dietary and metabolic outcomes without increasing the psychological burden. The combined group showed the greatest benefits. Findings highlighted the importance of considering automatic processes in diabetes management.