Depression Status and Incident Diabetes
summarizes the characteristics of the participants without prevalent type 2 diabetes by baseline depression status. Compared to the referents (MHI-5 score 86–100), women with higher depressive symptomatology were more likely to be younger, have no spouse and smoke cigarettes, and less likely to consume alcohol and be physical active. Participants with depressed mood had elevated BMI levels than those least depressed.
Characteristics of women without prevalent diabetes by depressive symptomatology status in the Nurses’ Health Study in 1996 (n=57880)a
During 10-year follow-up (531097 person-years), 2844 incident cases of type 2 diabetes were documented (). Compared to the referents (MHI-5 score 86–100), age-adjusted RRs of developing type 2 diabetes for women with MHI-5 score 76–85, 53–75, and depressed mood were 1.07 (95% CI, 0.97–1.17), 1.24 (95% CI, 1.11–1.38), and 1.42 (95% CI, 1.28–1.58), respectively (P for trend <0.001). The RRs were slightly attenuated by including marital status and family history of diabetes in the model, and remarkably attenuated after controlling for lifestyle factors (particularly physical activity) and BMI categories, but remained significant with RRs 1.17 (95% CI, 1.05–1.30) for those with depressed mood (P for trend = 0.002).
Relative risk (95% CI) of incident diabetes according to the depressive symptomatology status between 1996 and 2006.
We further categorized the participants with depressed mood into three groups: women with only SDS (MHI-5 score ≤52), with physician-diagnosed depression but not with antidepressants, and with antidepressant medications. In the fully adjusted Cox model, only women using antidepressant medications had a significant increased risk of incident type 2 diabetes compared to those with MHI-5 score 86–100 (RR, 1.25; 95% CI, 1.10–1.41), whereas individuals with only SDS or diagnosed depression were not at increased risk (). A complementary analysis using data from 2000 and 2006 revealed that those using SSRIs had 15% increased risk of incident diabetes (RR, 1.15; 95% CI, 1.01–1.31), while using other antidepressants (mainly TCAs) was not significantly associated with risk of developing diabetes (RR, 1.10; 95% CI, 0.91–1.33). However, multiple antidepressants use was associated with a much higher risk (RR, 1.51; 95% CI, 1.09–2.11; data not shown in tables).
Diabetes Severity and Incident Clinical Depression
The characteristics of the participants without prevalent depressed mood by diabetes status are depicted in . Compared to non-diabetic women, those with diabetes were more likely to be older, and have no spouse, and less likely to consume alcohol and be physical active. Participants with diabetes had elevated BMI levels than non-diabetic individuals.
Characteristics of women without depressed mood by diabetes status in the Nurses’ Health Study in 1996 (n=56857)a
During 10 years of follow-up (474722 person-years), 7415 incident cases of clinical depression were documented. As shown in , compared to non-diabetics, the RRs of developing clinical depression in participants with type 2 diabetes were 1.44 (95% CI, 1.33–1.57) in the age-adjusted model. The RR decreased to 1.29 (95% CI, 1.18–1.40) after adjustment for the covariates. Controlling for some major comorbidities (hypertension, hypercholesterolemia, coronary heart disease, and cancer) attenuated the association but it remained significant (RR, 1.20; 95% CI, 1.10–1.31, data not shown). Similar results were found in the sensitivity analysis which excluded those with other antidepressant medication use while free of SSRIs use or self-reported physician-diagnosed depression (data not shown).
Relative risk (95% CI) of incident clinical depression according to diabetes status between 1996 and 2006
We then further divided the diabetic participants into three groups (without any medications, only with oral hypoglycemic agents and with insulin therapy) to reflect the severity and management of the disease. Age-adjusted RR of developing clinical depression was 1.36 (95% CI, 1.19–1.55), 1.42 (95% CI, 1.25–1.60), and 1.78 (95% CI, 1.47–2.15) for diabetic women without medications, with oral hypoglycemic agents, and with insulin therapy, respectively (P for trend <.001). These associations remained significant with adjustment for the covariates (RR, 1.25; 95% CI, 1.09–1.42; RR, 1.24; 95% CI, 1.09–1.41; RR, 1.53; 95% CI, 1.26–1.85, respectively). Incorporation of major comorbidities markedly dropped the RRs but they remained statistically significant.