The current study validated the relationship between inhibitory control and dietary compliance among patients with type 2 diabetes mellitus based on subjective and objective measures. These findings provide a scientific theoretical basis and a new intervention target to improve dietary compliance among patients with T2DM. To the best of our knowledge, the current study was one of the first to comprehensively analyze the relationship between inhibitory control and dietary compliance in patients with T2DM by using both subjective and objective measures in the same study.
Dietary compliance refers to the consistency between patients’ dietary behavior and their doctors’ advice in the process of receiving treatment[28]. Dietary compliance is the most important index to measure the dietary self-management behavior of patients with diabetes. By evaluating the dietary compliance of patients with T2DM, targeted dietary guidance can be given to patients, which is conducive to delaying the occurrence of diabetic complications and improving the quality of life of patients[34]. However, dietary compliance in patients with T2DM is low, and it is influenced by many factors. This study showed that dietary compliance was significantly different among different categories of age, gender, education level, hypoglycemia in the past year, glycated hemoglobin A1c (HbA1c) and body mass index (BMI). Further analysis showed that female elderly patients with a higher education level and history of hypoglycemia in the past year tended to have higher dietary compliance among patients with T2DM. Moreover, patients with HbA1c and BMI within the normal range have higher dietary compliance, but based on the literature and clinical experience, we generally believe that HbA1c and BMI are dependent on dietary compliance[40–42].
In addition, this study also found a significant correlation between inhibitory control and dietary compliance among patients with T2DM based on both subjective and objective measures. The correlation persisted after controlling for sociodemographic characteristics and negative emotions. To the best of our knowledge, this is the first study to comprehensively explore the relationship between inhibitory control and dietary compliance among patients with T2DM by combining both subjective and objective measures. Although recent neuroimaging findings suggest that the two sets of measures share a common neuroanatomical substrate[43], some suggest that performance-based tasks assess underlying skills, while rating scales assess the application of those skills in daily life[44]. Thus, they measure different aspects of inhibitory control. In addition, inhibitory control is a multifaceted concept, and different types of inhibitory control can be reflected by different objective cognitive tests; for example, the stop signal task assesses a person’s response inhibition ability, and the Stroop task assesses a person’s conflict control ability. Therefore, although both subjective and objective measures of inhibitory control were significantly associated with dietary compliance, the results were not completely consistent.
In the case of specific results relating to subjective measures, the t score of inhibitory control was negatively correlated with the total score and all dimensions of dietary compliance. Namely, the poorer the level of inhibitory control, the worse the dietary compliance in patients with T2DM. This study is one of the first to reveal the relationship between inhibitory control and dietary compliance in patients with T2DM by using rating scales. In other words, patients’ perceived (i.e., subjective) inhibitory control dysfunction can be utilized by medical staff in determining their patients’ specific challenges in following diabetic diet control. This result has important clinical significance for improving dietary compliance among patients with T2DM.
In the case of specific results related to objective measures, this study revealed a significant correlation between inhibitory control measured by cognitive tests and dietary compliance in patients with T2DM. Specifically, general response inhibition based on stop signal task measurements was not significantly associated with the total scores of dietary compliance, which was consistent with a previous study[28]. However, further analysis found that general response inhibition was significantly related to carbohydrate and fat compliance behavior; that is, the stronger the general response inhibition ability, the better the compliance behavior related to dietary carbohydrate and fat intake. This result was similar to that of a previous study. Hofmann et al.[45] identified that high general response inhibition decreased the influence of implicit preferences on eating behavior. These results have consistently demonstrated that higher response inhibition buffers the effect of the impulsive system on eating behavior, whereas lower response inhibition induces the opposite pattern[45]. On the other hand, the level of conflict control measured by the Stroop task was significantly correlated with the total score of dietary compliance and two of its dimensions (carbohydrate and fat compliance behavior and oil and salt compliance behavior). Namely, the stronger the conflict control ability, the better the dietary compliance of patients with T2DM, especially in the compliance behaviors related to dietary carbohydrate and fat intake and oil and salt consumption. To the best of our knowledge, this is the first study to reveal the relationship between conflict control and dietary compliance among patients with T2DM. For patients with diabetes, a low-carbohydrate, low-fat, light diet contributes to controlling blood glucose, but these foods are often not delicious enough to bring pleasure to patients. Thus, when faced with a variety of food temptations, some patients with poor conflict control ability may show self-management relaxation and compromise to enjoy the momentary pleasure brought by food, thus demonstrating decreased dietary compliance. Therefore, when treating patients with poor dietary compliance, health care providers should consider the underlying factor of impaired inhibitory control.
However, there were several limitations in our study that should be considered. First, the generalizability of our findings is limited since all of the patients were recruited from only three hospitals. Second, we could not make inferences about the causality between inhibitory control and dietary compliance because we had only cross-sectional data. Therefore, longitudinal studies should be carried out to further clarify the problem. Third, future studies should combine electroencephalogram, magnetic resonance imaging and other research methods to explore the neural mechanism of inhibitory control in patients with different levels of dietary compliance to provide a theoretical basis for further training intervention.