Psychosocial Factors in Diabetes Management 197effects of stress on type 2 diabetes is somewhat more consis-
tent in both animal and human studies. Stress and stress
hormones have been more consistently shown to produce hy-
perglycemic effects in type 2 diabetes. Animal and human
studies provide evidence of autonomic nervous system abnor-
malities in the etiology of type 2 diabetes, with exaggerated
sympathetic nervous system activity affecting glucose metab-
olism. Although additional evidence is needed, the effects of
stress management techniques appear to have more bene“cial
effects in type 2 diabetes.
Depression in Diabetes
Substantial research indicates that depression is three to four
times more prevalent among adults with diabetes than among
the general population, affecting one in every “ve patients
(Lustman, Grif“th, & Clouse, 1988). In addition, evidence
suggests that in both types of diabetes depressive episodes
tend to last longer in comparison to individuals without dia-
betes (Talbot & Nouwen, 2000). The effects of depression on
diabetes management, its etiology, assessment, and treatment
are reviewed in the next section.
Etiology
The etiology of depression in diabetes is not yet fully under-
stood. However, an increasing number of studies have in-
vestigated potential causal mechanisms underlying these
coexisting conditions. A thorough review (Talbot & Nouwen,
2000) attempted to identify support for two dominant
hypotheses linking depression and diabetes: (a) depression
results from biochemical changes directly due to the illness
or its treatment, and (b) depression results from the psy-
chosocial burden of having a chronic medical condition, not
from the disease itself. Instead of evidence in support of
these hypotheses, the “ndings support a relationship between
the presence of major depressive disorder (MDD) or depres-
sive symptomatology and increased risk of developing type
2 diabetes and diabetes-related complications. Thus, in ac-
cordance with a diathesis-stress framework, metabolic
changes (e.g., insulin resistance) resulting from MDD may
trigger an individual•s biological vulnerability to developing
type 2 diabetes (e.g., Winokur, Maislin, Phillips, & Amster-
dam, 1988). Patterns regarding causality of MDD are less
clear for type 1 diabetes (Talbot & Nouwen, 2000). There is
speculation that MDD is a consequence of having type 1 dia-
betes, since the “rst episode of MDD generally follows the
diagnosis of diabetes. Future prospective studies with type 1
diabetes patients, their self-care regimen, and adherence level
should help clarify this issue.
Impact of Depression in DiabetesThe comorbidity of depression and diabetes can have sub-
stantial and debilitating effects on patients• health. This
may occur either directly via physiological routes or indi-
rectly through alterations in self-care. Lustman, Grif“th, and
Clouse (1997) developed an empirically based model in
which depression has direct and indirect links to glucose dys-
regulation and risk of diabetes complications. In this model,
depression is directly associated with obesity, physical inac-
tivity, and treatment noncompliance. These factors lead to the
risk of diabetes complications. Depression is also directly re-
lated to diabetes complications as well as to speci“c behav-
ioral factors, such as smoking and substance abuse, that have
been found to increase the risk of disease complications.
According to this model, smoking cessation treatment and
weight loss programs would aid in the reduction of diabetes
complications. Unfortunately, however, depressed patients
are generally more resistant to such treatment approaches and
thus continue to compromise their diabetes management. In
further support of the mechanisms inherent in this model, the
presence of concomitant depressive symptoms among older
diabetic Mexican Americans was found to be associated with
signi“cantly increased health burden (e.g., myocardial in-
farction, increased health service use; Black, 1999). Thus,
treating depression in patients with diabetes is particularly
important in preventing or delaying diabetes complications,
stabilizing metabolic control, and decreasing health service
utilization.
Other studies have focused on the relationship between
depressive symptoms and medical outcomes. Results of a
meta-analysis including 24 studies in which research par-
ticipants had either type 1 or type 2 diabetes indicate that
depression is signi“cantly associated with hyperglycemia
(Lustman, Anderson, et al., 2000). Similar effect sizes were
found in studies of patients with both types of diabetes.
However, results differed depending on the assessment me-
thods utilized. To elucidate, larger effect sizes were found
when standardized interviews and diagnostic criteria were
employed to assess depression in comparison to self-report
questionnaires (e.g., BDI; Beck, Ward, & Mendelson, 1961).
According to the authors, it is possible that one of the rea-
sons for these results is the decreased speci“city of self-
report measures that capture not only depression but also
anxiety, general emotional distress, or medical illness.
Nonetheless, the authors assert that future research is needed
to determine the cause and effect relationship between de-
pression and hyperglycemia as well as the effect of depres-
sion treatment on glycemic control and the continuous
course of diabetes. In addition, Gary, Crum, Cooper-Patrick,