An Exploratory Prospective Intervention Study on Dietary Content and HbA1c in Experiential Nutrition Guidance for Patients with Type 2 Diabetes

Background: Medical nutrition therapy (MNT) is crucial for diabetes management. This study evaluated a hands-on nutrition education program that incorporated cooking demonstrations for glycemic control, anthropometrics, and dietary behavior over a 2-month period. Methods: Nineteen type 2 diabetes patients (four males and 15 females; 79% female) participated. The median [IQR] age was 70.0 [65.5–73.0] years; the duration of diabetes was 12.0 [8.5–14.0] years; the body mass index (BMI) was 24.3 [21.05–27.90] kg/m², and the baseline HbA1c level was 6.90 [6.55–7.50%]. Approximately 20–25% of patients used injectable therapies. Pre- and post-treatment comparisons were performed via Wilcoxon signed-rank tests, while effect sizes were quantified via rank–biserial correlation (RBC). Results: In females (n = 15), carbohydrate intake decreased significantly (RBC = −0.583; p = 0.050). The protein levels per 1000 kcal exhibited a strong positive effect (RBC = 0.550; p = 0.065). HbA1c levels improved significantly (overall: RBC = −0.689 and p = 0.009; females: RBC = −0.725 and p = 0.014), and while body fat increased significantly (overall: RBC = 0.979 and p < 0.001; females: RBC = 0.983 and p < 0.001), the skeletal muscle index tended to decrease in females (RBC = −0.333; p = 0.268). Conclusions: Short-term hands-on nutrition education resulted in significant HbA1c improvement and dietary behavior changes but was accompanied by body composition deterioration. The findings of this study clarify the potential risks of nutritional interventions in elderly diabetic patients and provide important insights for improving future programs.