Diabetes is a complex and burdensome disease that requires the person with diabetes to make numerous daily decisions regarding food, physical activity, and medications. Comorbid diabetes distress and depressive symptoms are prevalent emotional states in people with type 2 diabetes. Psychological problems could arise from stress of management diabetes and worrying about hypoglycemia and the complications of diabetes. Diabetes distress is defined as a patients’ concern about disease management, support, emotional burden and access to care, which views as part of diabetes spectrum and not a separate clinical psychopathology. Studies of meta-analysis suggested overall estimated prevalence of diabetes distress among type 2 diabetes patients is 36%, but co-occurrence of depressive symptoms is about 20%. Some studies conducted both depressive symptoms and diabetes distress in type 2 diabetes individuals were associated with medication non-adherence and poor self-management, worse glycemic control and lower health-related quality of life. However, evidence also suggested diabetes distress had been distinguished from depressive symptoms, in the linkages to self-care activities and glycemic control. Two cross-sectional studies indicated that diabetes distress but not depressive symptoms, was associated with self-management and glycemic control[3, 10]. However, another longitudinal study with 253 primary care type 2 diabetes patients suggested only depressive symptoms but not diabetes distress was associated with future diet, physical activity, and glucose testing self-care behaviors. Clearly, the effect of diabetes distress and depressive symptoms on diabetes self-care and glycemic control are well studied but mixed results. Thus, the potential pathways among psychological factors and diabetes outcomes need to be studied further.
Self-efficacy, a critical concept of social cognitive theory (SCT), is related to one’s belief and confidence in the ability to successfully perform a task and execute skills effectively. A high degree of self-efficacy is essential for carrying out self-care behaviors. Considerable evidence supported self-efficacy had direct effect of improving diabetes self-management, medication adherence, metabolic outcomes and HRQoL[13, 14]. A meta-analysis of 775 studies concluded that self-efficacy was all consistence with all adherence behaviors (e.g. dietary, physical activity) and diet adherence was the most significant predictors of HbA1c. Interestingly, several recently research highlighted self-efficacy as a potential mediator in the links between depression or depressive symptoms and diabetes management[16–18]. One study with 371 type 2 diabetes patients in Malaysia found both diabetes distress and depressive symptoms had indirect effect on self-care activities via self-efficacy. However, little is known about how psychological variables (e.g. depressive symptoms and diabetes distress) may stimulate diabetes management (e.g, physical activities, diet activities, glycemic control) at the same time, especially in the Chinese rural residents. Untangle the underlying pathways between psychological factors and specific diabetes self-management via self-efficacy is crucial.
Glycemic control is one of main goals of diabetes care. Recent studies focus more attention to possible mechanisms mediating the relationship between psychological variables and glycemic controls. Family members and friend support may contribute to better glycemic control by ameliorating the effects of diabetes distress. Perceived control had mediated the effect of diabetes distress on medication adherence and glycemic control. Self-efficacy of diabetes management as a mediator linked the relationship between depressive symptoms and glycemic control among males type 2 diabetes adults. However, few empirical findings exist regarding the relationship between diabetes distress and glycemic control mediated via self-efficacy. One study with 254 Chinese type 2 diabetes patients found depressive symptoms had only indirect effect on glycemic control through diabetes self-management, but not via self-efficacy. Therefore, studies are needed to empirically examine whether self-efficacy mediate the linkages among diabetes distress and glycemic control.
HRQoL as health being with type 2 diabetes has become increasingly important for diabetes control. A meta-analysis study has indicated that self-reported depressive symptoms in diabetes adults markedly impaired their HRQoL on several domains. Little is known about the independent effect of diabetes distress on HRQoL among diabetes adults. One study of 193 Chinese Type 2 diabetes patients demonstrated diabetes distress was significant associated with glycemic control, obesity and quality of life. Another study indicated diabetes distress and self-efficacy were related to HRQoL. Poorer quality of life and depressive symptoms also had been associated with increased out-of-pocket payment for health service utilization and more likely to be impoverished. Understanding how to distribute psychological care to diabetes patients with diabetes distress or depressive symptoms has important implications. Thus, further studies are deserved about the effect of diabetes distress and depressive symptoms on HRQoL and whether self-efficacy alleviate the two variables impact on HRQoL.
Diabetes distress, depressive symptoms and self-efficacy are correlated. Their relationships with diabetes management and health outcomes may not be clearly observed unless they are examined in the same statistical model. Yet, to date, no studies to our knowledge have examined the potential pathways and interactions among psychological factors (both diabetes distress and depressive symptoms), behavioral variables (self-efficacy), diabetes management (e.g., healthy diet, physical activity, medication adherence), glycemic control and HRQoL in the same study, especially for primary care type 2 patients in rural China. The current study examines whether diabetes distress and/or depressive symptoms is directly associated with diabetes outcomes, such as diabetes management, sequent 6-month glycemic control and HRQoL among Chinese primary care adults with type 2 diabetes. In addition, we examine whether self-efficacy mediates both psychological factors and behavioral predictors in relation to diabetes outcomes. Based on social cognitive theory and aforementioned studies, we present a conceptual framework (Fig. 1) and employ regression-based mediation analysis to testify our hypothesis. We hypothesize that: (1) high level of diabetes distress and depressive symptoms would directly decrease diabetes management and health outcomes. (2)self-efficacy affected by diabetes distress and depressive symptoms, which, in turn, determines diabetes self-care behaviors, subsequent diabetes glycemic control and HRQoL.