Substantial research has shown that Latinos exhibit a higher prevalence of type 2 diabetes, as well as poorer glycemic control (Harris, 2001
), more frequent complications, greater disease severity, and worse health outcomes than non-Latino whites (Centers for Disease Control and Prevention, 2008
). Less is known, however, about the psychosocial factors associated with glycemic control in this population. The current study investigated the relationship between social-environmental support resources for disease management and HbA1c among Latino men and women (majority of Mexican descent) with type 2 diabetes, and examined whether diabetes self-management and depression contributed to this association. Findings showed that individuals reporting greater support resources for disease management also reported more adaptive self-management behaviors and less depressive symptomatology, which in turn were associated with lower HbA1c levels.
Notably, based on estimates from previous research, the magnitude of the effect of support resources is likely to have clinically significant implications. Stratton and colleagues (2000)
reported that a 1% decrease in HbA1c was associated with a reduction in the relative risk by 21% for any end point related to diabetes, 21% for diabetes-related mortality, 14% for myocardial infarction, and 37% for microvascular complications. In the present study, a one standard-deviation increase in support resources was associated with roughly a 0.3% decrease in HbA1c. Drawing on findings from the UK prospective diabetes study (Stratton et al.), an improvement of this magnitude translates to a relative risk reduction of approximately 7% for mortality, and from about 5 to 12% for a variety of other adverse diabetes-related health outcomes.
Glycemic control is partly dependent upon the regular completion of several self-management behaviors, including exercise, dietary modification, foot-care, self-monitoring of blood glucose, and medication adherence (American Diabetes Association, 2002
). A variety of interventions aimed at improving self-management in individuals with diabetes have resulted in significant decreases in HbA1c over time (Chiu, et al., 2009
; Gold, et al., 2008
; Ruggiero, et al., 2010
). Consistently, we identified an inverse association between diabetes self-management and HbA1c levels in the present study, highlighting the importance of implementing effective diabetes self-management training programs to achieve better health outcomes among individuals with type 2 diabetes. Such programs may be especially critical in Latinos, who often lack access to healthcare services (Anders et al., 2008
), and who frequently exhibit poor adherence to treatment recommendations even when they do have access. For instance, less than 60% of Latino adults with type 2 diabetes receive annual eye and foot exams, and participate in daily blood glucose monitoring (Centers for Disease Control, 2005). Moreover, Latinos with type 2 diabetes perceive self-monitoring of blood glucose as more difficult and have more negative perceptions about future health and well-being relative to Asians, African-Americans, and non-Latino whites with the same condition (Misra & Lager, 2009
These findings demonstrate the need to identify effective resources for promoting more adaptive self-care in this at-risk population. Integration in a supportive social network can serve this purpose (Barrera et al., 2008
), and could be particularly facilitative in Latinos given cultural norms emphasizing the importance of close interpersonal relationships (Marin, 1993
; Sanchez-Burks et al., 2000
). For instance, encouragement from family members was associated with greater intention to complete blood glucose, cholesterol, and blood pressure screenings in a sample of Mexican-American adults (Ashida, Wilkinson, & Koehly, 2010
). Consistent with these findings, individuals in the present study who reported receiving greater support resources for disease management reported better adherence to self-management behaviors, and in turn, exhibited lower HbA1c levels. As such, support resources represent an important potential target for interventions aiming to improve diabetes self-management, and thus, glycemic control among Latinos with type 2 diabetes. In fact, Barrera et al. (2006)
evaluated an intervention that directly targeted social-environmental support resources for disease management as a mechanism to improve health behaviors and outcomes, and found that increases in support mediated positive intervention effects on fat consumption, exercise, and glycemic control at a 6-month follow-up. In addition to representing a target for change, support resources for disease management may also represent a mechanism that, once mobilized, helps to sustain the effects of an intervention long after treatment has ended. In a follow-up to their initial investigation, Barrera and colleagues (2008)
reported that changes in support resources during year one influenced changes in some outcomes for up to two years post-baseline.
In addition to being more common among individuals with type 2 diabetes, depression has also been associated with poor glycemic control (Lustman, et al., 2000
), increased diabetic symptoms, more frequent complications, and poorer health outcomes (Black et al., 2003
; de Groot et al., 2001
; Katon et al., 2005
). In a study conducted by Gross and colleagues (2005)
, over 30% of Latino participants with diabetes reported depressive symptoms in the moderate to severe range; these participants exhibited significantly higher HbA1c levels than participants without elevated depression. Consistent with these and other previous findings (for a review, see Lustman et al.), greater depressive symptomatology was associated with higher HbA1c levels in the present study. One potential explanation that has been put forth to explain this relationship is that depression leads to poorer diabetes self-management (Gonzalez, et al., 2008
), which in turn, results in poorer glycemic control. Specifically, symptoms that characterize depression, such as low energy and motivation, may interfere with individuals’ ability to follow diabetes treatment recommendations. However, although greater depression symptomatology was associated with poorer diabetes self-management in the present study, the indirect effect of depression on HbA1c via diabetes self-management was not statistically significant. Further research is needed to investigate the mechanisms underlying the link between depression and glycemic control (Lustman et al.), which are likely to involve a complex combination of both behavioral and physiological factors. In regard to the latter, depression has consistently been associated with physiological alterations including activation of the hypothalamic-pituitary-adrenal axis, sympathetic nervous system, and proinflammatory responses, which can induce insulin resistance and contribute to poorer diabetes-related health outcomes (Golden, 2007
Regardless of the underlying mechanism, the present findings speak to the value of early and frequent screenings for depression in individuals with diabetes. The associations of depression with diabetes self-management and poor glycemic control also highlight the importance of developing and implementing interventions in the primary care setting to intervene in the deleterious reciprocal relationship between depression and type 2 diabetes (Mezuk, Eaton, Albrecht, & Golden, 2008
). Consistent with previous research (e.g., Connell et al., 1994
), the present findings point to support resources as an important protective factor in the development of depression in individuals with a chronic illness. Specifically, greater support resources for disease management was associated with fewer depressive symptoms, and thus lower HbA1c levels.
There are several caveats that should be considered in the interpretation of these findings. First, the cross-sectional design of this study precludes inferences about causation. The proposed causal sequence was a better statistical fit to the data than was the reverse sequence (i.e., from HbA1c to support resources for disease management via depression and/or diabetes self-management); however, additional (prospective) research is needed to determine whether increasing support resources for disease management consistently results in better diabetes self-management, less depression, and thus, better glycemic control over time. Second, because information about medication use was not available, analyses did not control for potential effects of medication on glycemic control or reported depressive symptoms. Third, the results should be interpreted in the context of sample characteristics (i.e., majority were female, low income, and low U.S.-acculturated as indicated by language preference). Because our sample was relatively homogeneous, we were unable to investigate gender, socioeconomic status, or acculturation as potential moderators of the direct or indirect effects in this model. Further, the fact that the majority (but not all) of the participants were of Mexican descent may limit the generalizability of the findings to other segments of the Latino population, and prevent an examination of potential ethnic or cultural differences. Additional research is needed to determine whether or not the links among support resources for disease management, diabetes self-management, depression, and ultimately, glycemic control, persist outside of the studied population.
Despite these limitations, the present study provides additional support for the well-established link between health and social support, extends the research base on social-environmental support and resources specifically related to managing a chronic health condition, and suggests two potential mechanisms underlying the link between support and resources for disease management and glycemic control in individuals with type 2 diabetes: diabetes self-management and depression. Importantly, these findings also point to support resources for disease management as a potential target for efforts aiming to improve diabetes self-management, reduce depression, and thus, improve glycemic control. Due to the importance of family interdependence and close social relationships in the Latino culture, especially in the context of adverse circumstances such as managing one’s diabetes, social-environmental support and resources for disease management may represent an especially important area for interventions aiming to improve the mental and physical health of this population.