Abstract
Background/Objectives: Diabetes mellitus type 2 (T2D) is a global epidemic affecting over 500 million adults. Glycemic load (GL) and beta-glucan intake are modifiable dietary factors related to T2D risk that are largely shaped by the choice of cereal-based foods. This theoretical study derives fuzzy sets for GL and beta-glucan to enable their joint nutritional evaluation within a multidimensional framework and uses the framework to derive a dietary circle oriented toward T2D prevention. Methods: Fuzzy membership functions for GL and beta-glucan were constructed based on epidemiological dose–response data, guideline values, and authorized health claims. These functions were integrated into an existing fuzzy evaluation system that aggregates the evaluations of nutrient intake using a Schweizer–Sklar T-norm (p = 6). A fuzzy optimization algorithm was applied to the food quantities underlying the current German food-based dietary guidelines. Results: The GL fuzzy set evaluates intakes below 80 g/d as desirable and penalizes intakes above 160 g/d; the beta-glucan fuzzy set evaluates intakes of at least 3 g/d as good, with an optimum at 6 g/d. Fuzzy optimization shifted the diet markedly toward vegetables, legumes, fish, and tofu while strongly reducing cereals and milk products, and GL decreased from 161 to 77 g/d. The resulting dietary circle achieved an evaluation >0.9 for the intake of every nutrient considered and an aggregate score of 0.894. Conclusions: Integrating GL and beta-glucan into the fuzzy evaluation framework yields a coherent, food-based dietary circle oriented toward T2D prevention that can serve as a reference for counseling, menu planning, and intervention studies; its preventive effect remains to be tested.