Purpose As the French West Indies are facing an ongoing nutrition transition with increasing type-2 diabetes mellitus (T2DM) prevalence, our study aimed to evaluate the effect of potential shifts in dietary patterns on T2DM risk in French West Indian adults according to several scenarios. Methods We used a cross-sectional multistage sampling survey on dietary intake conducted in 2013 on a representative sample of Guadeloupeans and Martinicans adults (n = 1063). From previously identified current dietary patterns, we used PRIME-Diabetes, a comparative risk assessment model, to estimate the effect of potential shifts from the “transitioning” pattern to the “convenient,” the “prudent,” and the “traditional” ones on T2DM risks. Results Potential shift in dietary intakes from the “transitioning” pattern to the “traditional” one reduced the T2DM risk in women (− 16% [− 22; − 10]) and in men − 14% [− 21; − 7]), as the shift in dietary intakes toward the “prudent” pattern (− 23% [− 29; − 17] and − 19% − 23; − 14], respectively). These risk reductions were mostly driven by increased whole grains, fruits, green leafy vegetable intakes, and decreases in potatoes, red meats, processed meats, and sugar-sweetened beverages. The shift in dietary intakes toward the “convenient” pattern did not affect the T2DM risks. Conclusion To curb the increase in T2DM prevalence and reduce this burden, one public health action could be to target transitioning adults and help them to shift towards a diet associated with a reduced risk of T2DM as a prudent or a traditional diet.