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General Hospital Psychiatry 25 (2003) 246–252
The relationship of depressive symptoms to symptom reporting,
self-care and glucose control in diabetes
Paul S. Ciechanowski, M.D.,MPH a, *, Wayne J. Katon, M.D. a , Joan E. Russo, Ph.D a ,
Irl B. Hirsch, M.D. b
a Department of Psychiatry and Behavioral Sciences, University of Washington, Seatlle, WA 98195, USA
b Department of Medicine, University of Washington, Seattle, WA, USA
Depressive symptoms are common among patients with diabetes and may have a significant impact on self-management and health
outcomes. In this study we predicted that: 1) there would be a significant association between depressive symptoms and diabetes symptom
burden, physical functioning, diabetes self-care, and HbA1c levels; and, 2) that the association between depressive symptoms and HbA1c
levels would be significantly greater in type 1, as compared to type 2 diabetic patients. This cross-sectional observational study of 276 type
1 and 199 type 2 diabetes patients took place in a tertiary care specialty clinic. We collected self-reported data on depressive symptoms,
complications, medical comorbidity, diabetes symptoms, diabetes self-care behaviors, physical functioning, and demographics. From
automated data we determined mean HbA1c levels over the prior year. We performed linear regression analyses to assess the association
between depressive symptoms and diabetes symptom perception, diabetes self-care behaviors, physical functioning, and glycemic control.
Among patients with type 1 and 2 diabetes, depressive symptoms were associated with greater diabetes symptom reporting, poorer physical
functioning, and less adherence to exercise regimens and diet. There was a significant association between depressive symptoms and HbA1c
levels in type 1, but not type 2 diabetic patients. Because of their association with clinical aspects of diabetes care such as diabetes symptom
reporting and adherence to diabetes self-care, depressive symptoms are important to recognize in treating patients with diabetes. © 2003
Elsevier Inc. All rights reserved.
Keywords: Depression; Diabetes; Diabetes symptoms; Self-care; Glucose control
1. Introduction
While a number of cross-sectional studies have shown
that depression is significantly associated with hyperglyce-
mia in type 2 diabetic patients, as many studies have found
that this association is not significant [5]. When examined
meta-analytically, the association between poorer glucose
control and depression has been found to be more signifi-
cant in type 1 as compared to type 2 diabetic patients across
studies, particularly when standardized interviews were
used (Effect Size 0.28 vs. 0.15) [5]. A recent cross-sectional
study also found the correlation between Beck Depression
Inventory scores and HbA1c levels in type 1 diabetic pa-
tients was moderately high ( r
A recent meta-analysis has shown that among patients
with diabetes, the prevalence of major depression and sig-
nificant depressive symptoms was 11% and 31%, respec-
tively [1]. The presence of comorbid depressive symptoms
can have a significant impact on health outcomes, health
care utilization, and overall functioning in patients with
diabetes [2,3]. In a recent study of predominantly type 2
primary care diabetes patients ( N
.44) as compared to that in
.06) [6]. A number of differ-
ences in type 1 and 2 diabetes – such as different etiologies,
age of onset and treatment regimens – may lead to different
mechanisms operating to cause hyperglycemia in depressed
type 1 and 2 diabetic patients. In type 1 diabetes, patients
develop complete insulin deficiency due to an autoimmune
destruction of the beta cells of the pancreas. In type 2
* Corresponding author. Tel.: 1-206-543-8848; fax: 1-206-221-
E-mail address: (P. Cliechanowski).
0163-8343/03/$ – see front matter © 2003 Elsevier Inc. All rights reserved.
367), we found that de-
pressive symptoms were associated with significantly
poorer physical and mental functioning, decreased adher-
ence to dietary recommendations, less adherence to oral
hypoglycemic medications, higher health care costs and
nonsignificant increases in HbA1c levels [4].
type 2 diabetic patients (r
736496.002.png 736496.003.png 736496.004.png
P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252
diabetes there is a relative lack of insulin based in part on
resistance to this hormone at both the liver and the muscle.
The complete insulin deficiency in type 1 diabetes may
result in greater lability in glycemic control in response to
behavioral or neuro-hormonal effects of depression, than
may be the case in type 2 diabetes. There is also typically
more treatment heterogeneity in type 2 patients who may be
treated with diet and exercise only, oral hypoglycemics,
insulin or a combination of these. The main – and essential
– treatment in type 1 diabetes is insulin, though diet and
exercise also play an important secondary role in achieving
glucose control. Such differences in diabetes treatment may
result in differential treatment outcomes given changes in
self-care behavior resulting from depression. For example,
in a type 2 diabetic patient treated with diet only, lack of
treatment adherence is not likely to cause as significant an
increase in glucose levels as lack of adherence to an insulin
regimen in a type 1 diabetic patient.
Another important feature of the coexistence of diabetes
and depression is the increased potential for symptom re-
porting among depressed diabetic patients. While there is
overlap of symptoms associated with both disorders (e.g.,
fatigue, hyperphagia), depression is known to cause non-
specific symptom amplification in patients with chronic
medical illnesses [7]. Thus, patients with depression may
have a lower threshold in reporting all physical symptoms
including common diabetes symptoms such as thirst, poly-
uria, and blurry vision. This tendency to amplify physical
symptoms may result in higher health care use and in-
creased laboratory testing by providers [8].
In the current study, we assessed the impact of depres-
sive symptoms on patients with diabetes in a tertiary care
university-based clinic. We sought to determine if diabetes
self-care behaviors, physical functioning, diabetes symptom
reporting and glucose control correlated significantly with
depressive symptoms in both type 1 and 2 diabetes. We
hypothesized that higher levels of depression would be
significantly associated with greater diabetes symptom re-
porting, lower diabetes self-care, lower physical functioning
in both type 1 and 2 diabetes, and we predicted that there
would be effect modification so that higher levels of depres-
sion would be significantly associated with higher HbA1c
levels in type 1, but not type 2 diabetes.
the study and requested permission for a review of their
automated records. Subjects not returning the questionnaire
within three weeks were sent an identical second question-
naire and consent form. Subjects received a $3 compensa-
tion for their time in participating in the study. The ques-
tionnaire and all patient correspondence were approved by
the University of Washington institutional review board.
2.1. Self report instruments
2.1.1. Depression
The Hopkins Symptom Checklist-90, Revised (SCL-
90-R) [9] is a self-report instrument, that has been validated
in previous studies of medical patients and has been found
to be highly reliable [10,11]. The twenty items from the
depression and additional symptom subscales (SCL-20)
were used in the current study.
2.1.2. Diabetes complications
Patients were given a score from 0–3 to reflect the
number of self-reported diabetes-related complications from
the following: retinopathy, nephropathy, and peripheral
neuropathy [12]. This method has been shown to be highly
correlated with ratings of severity of diabetes from indepen-
dent physicians ( r
.001) [12].
2.1.3. Medical comorbidity
Based on the methods of Wells et al. [13], we estimated
medical comorbidity by having patients check whether they
did or did not have each of eighteen medical conditions
(e.g., asthma, hypertension, ulcer) on a checklist. The total
number of conditions was calculated by summing positive
responses and for analyses each patient was given a score of
0, 1, 2 or more than 2 medical conditions.
2.1.4. Diabetes self-care
The Summary of Diabetes Self-Care Activities [14] is a
12-item questionnaire that measures absolute levels of self-
care behavior and the percentage of activities recommended
by the physician that were actually performed. This ques-
tionnaire has been shown to be a valid and reliable measure
of diabetes self-management in multiple trials. In this study,
diet amount, diet type, exercise, and glucose testing were
assessed, and since items within each domain have different
scales, raw scores for each were converted to standard
scores having a mean of 0 and an SD of 1. Standardized
scores were averaged to form a composite z score for each
regimen behavior. A higher z score indicates better adher-
ence to the self-care behavior.
2. Materials and methods
This cross-sectional observational study was carried out
at the University of Washington Diabetes Care Center
(DCC), Seattle, Washington. Eligible participants included
all English-speaking DCC patients already enrolled in both
1998 and 1999, age 18 or over. Potential subjects with
severe cognitive or language deficits were excluded. In July
1999, 826 potential subjects were sent an approach letter
briefly describing the study. Two weeks later subjects were
sent a questionnaire and consent form which fully explained
2.1.5. Functional impairment
The Short-Form 12 Health Survey (SF-12) [15] is a
generic measure of health status that is a shorter version and
valid alternative to the SF-36 [16]. The SF-12 measures
functioning in medical populations and assesses physical
functioning, role limitations due to physical health prob-
.72, P
P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252
lems, bodily pain, general health, and social functioning,
which are represented in mental and physical component
scores. We report only the physical component score since
there is typically strong collinearity between depression and
the mental functioning score.
the significance of the demographic variables [age, gender,
marital status, education, race and income] was tested using
backward and forward stepwise techniques in the first step.
Only significant demographic variables were retained in the
models. In the second step, medical comorbidity and num-
ber of diabetes complications was forced into each model.
In the third and fourth steps diabetes type (type 1
2.1.6. Symptom reporting
To assess diabetes symptoms, we used the Self-Comple-
tion Patient Outcome [17] instrument to measure the fol-
lowing diabetes symptoms: blurred vision, thirst, polyuria,
excessive hunger, shakiness, fatigue, parasthesias, and feel-
ing faint. Items were rated on a Likert scale and we calcu-
lated the total number of symptoms that were experienced at
least “several days” in the past month.
Demographic and clinical data were determined from
questionnaire responses (race, education, income, and mar-
ital status) and from automated data (age, gender and dia-
betes type). We also used automated data to determine mean
glycosylated hemoglobin (HbA1c) values for each subject
from the preceding twelve months. Mean number of HbA1c
tests in this population was 2 per year (range 0–6). To
analyze HbA1c levels, the University of Washington DCC
uses a Bayer DCA2000, which is certified by the National
Glycohemoglobin Standardization Program as having doc-
umented traceability to the Diabetes Control and Compli-
cations Trial Reference Method.
1; type
0) and depression score were entered, respectively. In
the model assessing the association between depression and
HbA1c levels, the a priori hypothesis that diabetes type
would modify this association was tested by forcing in, as
the fifth step, the interaction of diabetes type and depres-
3. Results
Of 826 patients, 475 (58%) responded to the survey, of
which 276 (58%) had type 1 diabetes and 199 (42%) had
type 2 diabetes. There were no significant differences be-
tween respondents and nonrespondents in age (48.8
vs. 50.0
16.4, respectively; t
1.13, df
825, P
.26) and
All subsequent analyses are based on those respondents who
had at least one HbA1c level documented in the electronic
records within a twelve-month period ( N
( df
1 )
0.04, P
407). Clinical
and demographic characteristics of the respondents are out-
lined in Table 1.
2.2. Diabetes classification
Subjects were classified in this clinic based on their
clinical characteristics. In general, individuals with type 1
diabetes presented in childhood, adolescence, or as young
adults with acute symptoms, often ketoacidosis. Those with
type 2 diabetes usually presented later in life and were
overweight. Since 1991 the clinic staff has had access to the
measurement of islet antibodies (islet cell antibody, glu-
tamic acid decarboxylase, insulinoma-associated-2 autoan-
tibodies, and insulin autoantibodies) and in those cases
where the diagnosis was not obvious, these antibodies were
measured. If one of these antibodies was positive the patient
was considered to have type 1 diabetes.
3.1. Glycemic control
In the multiple regression model (Table 2), being married
was associated with a lower HbA1c level, whereas number
of complications was strongly positively associated with
HbA1c level. There was a significant statistical interaction
of diabetes type and depression with respect to HbA1c level.
We chose clinically meaningful cut-scores to illustrate this
interaction in Fig. 1. A cut-score of 1.72 on the SCL-20 is
associated with the highest positive predictive value for the
diagnosis of major depression [18]. A cut-score of 8% for
HbA1c levels was chosen since current clinical guidelines
recommend additional clinical action for patients whose
HbA1c levels are above this range [19]. The proportion of
subjects with HbA1c levels over 8% was significantly
higher among patients with type 1 diabetes who were de-
pressed (66.7%) compared to those with type 1 who were
not depressed (38.6%) as well as compared to both de-
pressed and nondepressed type 2 diabetes patients (37.5%
and 40.3%, respectively) (
2.3. Statistical analysis
2 tests with corrections for continuity were
used to compare respondents and nonrespondents on age
and gender. Appropriate human subjects approval to utilize
aggregate data of nonrespondents on these variables was
Multiple regression modeling with a combination of hi-
erarchical and stepwise techniques was used to determine if
depressive symptoms were associated with the following
dependent variables: HbA1c levels, diabetes symptoms,
self-care behaviors [diet type, diet amount, exercise, glu-
cose monitoring] and physical functioning. In each model
Because we looked at HbA1c over the prior year, and the
self-report measure of depression asks about symptoms in
the past 2 weeks, we conducted a sensitivity analysis to
examine the correlation of depression and HbA1c levels
when only considering those HbA1c levels from the past 4
months ( N
( df
3 )
9.6, P
146), after control-
ling for the covariates from the linear model (married status
253) and past 2 months ( N
gender (52.5% in both groups;
Data were analyzed using SPSS 10.0 for Windows. Two-
tailed t tests or
P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252
Table 1
Demographic and clinical characteristics by diabetes type
Diabetes Type
Total (N 407)
Type 1 (N
Type 2 (N
Age (years)
HbAlc (%)
SCL-20 score*
2 (df 1)
Female gender
Caucasian race
At least 1 year college
Married or cohabitating
Income $40,000
At least 1 medical comorbidity
At least 1 diabetes complication
Diabetes treatment in type 2
diabetes patients
Insulin only
Oral hypoglycemics only
Insulin and oral hypoglycemics
Diet only
* Range of SCL-20 values: type 1 diabetes: 0–3.4; type 2 diabetes: 0–3.3.
**Number of subjects on which percents are based varies because of missing data from some items. SCL Symptom Checklist
and complications). In type 1 and 2 diabetic patients the
correlations were: 1) for 4 months, r
.33, P
.001, r
which represent a mixture of dysthymic, and minor and
major depressed patients, as well as patients with adjust-
ment disorders with anxious and/or depressed mood [20–
NS, respectively; and, 2) for 2 months, r
.42, P
.14, NS, respectively. Therefore, when SCL-20 scores
and HbA1c levels were more tightly associated in time of
measurement, there was a higher correlation in type 1 dia-
betes between the two measures. The mean SCL-20 depres-
sion score in this sample (0.9
3.2. Diabetes symptom reporting
0.8) corresponds to a sub-
diagnostic range of depressive and anxiety symptoms,
In the multiple regression model assessing diabetes
symptom reporting, being married and higher education
Table 2
Multiple regression modeling of the association of depression and selected variables
Diet Amount Diet Type
3.50 .20** 3.23
marital status
.12** 2.78
Clinical covariates
.20 .01
.13* 2.46
.07 1.08
Diabetes type
.60 .05
.99 .18
2.85 .11
1.68 .11*
1.01 .41
Diabetes type
Overall model
F(6,361) 10.42,
R 2
F(6,362) 23.23,
R 2
F(6,364) 42.90,
R 2
F (5,351) 9.58,
R 2
F(5,359) 8.90,
R 2
F(5,361) 6.24,
R 2
F(4,305) .56,
R 2
p .0001
p .0001
p .0001
p .0001
p .0001
p .0001
p .69
*p .05, **p .01,
p .001
P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252
Fig. 1. Association between depression and HbA1c levels by diabetes type.
Depressed group has SCL-20 score 1.72, nondepressed group has
SCL-20 score 1.72.
Fig. 3. Association between depression quartiles and diabetes self-care.
Ranges of quartiles of SCL-20 depression scores are as follows: 1st: 0-.34;
2nd: .35-.69; 3rd: .70–1.35; 4th:1.36–3.40.
3.4. Diabetes self-care
were significantly associated with lower symptom reporting
whereas higher levels of diabetes complications and depres-
sion were significantly and independently associated with
more diabetes symptom reporting (Table 2). To illustrate
this relationship graphically, quartiles of depression were
used to derive means of symptom reporting in each quartile.
Fig. 2 shows the mean number of diabetes symptoms re-
ported as occurring at least several days in the prior month
by quartiles of SCL-20 depression scores.
Increasing age was significantly associated with higher
self-reported adherence to diet amount and type, while a
higher level of depression was associated with lower self-
reported adherence to diet amount, diet type and exercise.
Type 1 diabetes was significantly associated with higher
self-reported adherence with exercise. Glucose monitoring
was not associated with any of the variables in our model.
Fig. 3 illustrates the association between self-care and de-
pression for those domains of self-care that have been
shown to be significantly associated with depression (diet
type, diet amount and exercise). Again, depression severity
was grouped into quartiles and mean z-score for each do-
main of self-care was obtained for each quartile. As shown
in the figure, as depression increased, levels of diet and
exercise adherence decreased.
3.3. Physical functioning
Increasing age, and higher levels of medical comorbid-
ity, diabetes complications and depression were all signifi-
cantly associated with poorer physical functioning in our
sample, while higher income was associated with better
physical functioning (Table 2).
4. Discussion
Fig. 2. Association between depression quartiles and diabetes-related
symptom reporting. Number of symptoms refers to total number of diabe-
tes symptoms reported as occurring at least several days in prior month.
Ranges of quartiles of SCL-20 depression scores are as follows: 1st: 0-.34;
2nd: .35-.69; 3rd: .70–1.35; 4th: 1.36–3.40.
Depressive symptoms were found to be significantly
associated with lower adherence to dietary recommenda-
tions and exercise, poorer physical functioning, and higher
diabetes symptom reporting among patients with type 1 and
type 2 diabetes in a tertiary care diabetes specialty clinic.
These associations were robust after controlling for diabetes
type and complications. These results are consistent with
other studies. For example, in our previous study of a
primary care sample of predominantly type 2 diabetic pa-
tients, dietary recommendations were not followed as
closely in patients with greater levels of depression [4].
Common symptoms of depression such as changes in ap-
petite and decreased energy and motivation may signifi-
cantly affect diet and exercise. While changes in motivation
and concentration that occur in depression can conceivably
affect frequency of glucose monitoring, no evidence for this
could be found in our sample. In our previous study, we also
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