The aim of the present study was to evaluate the effectiveness of acceptance-based emotion regulation group therapy in improving disease control indices in patients with type 2 diabetes, a disease that is highly prevalent in Iran (a prevalence of about 1.3 to 14.5%). Our results showed that the intervention in the experimental group led to a significant decrease in HbA1c level and a significant increase in self-care and quality of life. The findings of the present study are consistent with those of the studies of Blackledge and Hayes (
30), Yao et al. (
31), and Izgu et al. (
32).
When a patient faces negative emotions, the metabolic system becomes out of balance, which in turn disrupts blood sugar regulation. During negative emotions, the secretion of adrenaline, light adrenaline, and other stress-related hormones increases from adrenal glands, and these hormones affect the liver by converting liver carbohydrate storage into glucose (sugar) to provide energy, leading to a rise in blood sugar level. Therefore, emotion regulation can lead to a decrease in blood sugar level (
33,
34).
According to studies, incompatibility with the disease and the lack of self-care behaviors have been usually associated with an avoidance-emotion-regulation style and non-expression of unpleasant emotions. Based on available evidence, avoiding emotions are associated with inconsistent consequences, and accepting and expressing them can encourage appropriate self-care behaviors (
35). Avoiding the disease and related emotions is very common in diabetics and can be a factor in not following self-care behaviors (
36). Furthermore, it can lead to the patient’s failure in following health care behaviors and adhering to treatment. Thus, accepting and expressing unpleasant emotions to achieve therapeutic goals can be adaptive and lead to increased self-care activities (
34). This finding is consistent with the results of Ramesh et al. (
37), who argued that adaptive emotion regulation strategies had a positive relationship with self-care behaviors.
In terms of the effectiveness of the acceptance component in controlling diabetes’ indices, it can be claimed that increasing acceptance in people with diabetes makes them more concerned about themselves and their health, so they try to take their medicines and insulin on time, better follow the diet recommended, do more physical activities, and measure blood sugar daily, which together improve the body’s metabolism and positively affect blood sugar, self-care behaviors, and finally quality of life (
38,
39). As a result, it can be stated that the findings of this study are consistent with the studies of Hadlandsmyth et al. (
40) and Gregg et al. (
41), who showed the effectiveness of acceptance and commitment therapies on the self-care of patients with type 2 diabetes. Furthermore, studies showed that mindful eating techniques, which were introduced to develop an individual’s understanding of the diet and nutrition and to increase patients’ mindful awareness with regard to eating, were effective in achieving favorable results (
42).
Therefore, emotion regulation education, by reducing unpleasant emotions and subsequent behaviors such as self-blame, blaming others, mental rumination, and boosting pleasurable emotions and subsequent behaviors such as acceptance, re-planning, and positive re-evaluation, can change this interactive relationship for the benefit of the patient and in a positive direction, for example, to improve diabetes control indicators.