Depression in Type 2 Diabetes Increases All-Cause Mortality Risk

Depression may increase the risk of all-cause mortality in individuals with type 2 diabetes mellitus (T2DM), but it is not specifically associated with cardiovascular mortality, according to a study published in BMC Psychiatry.

Researchers included individuals with T2DM (n=5695) from the National Health and Nutrition Examination Survey (NHANES) who provided depression measurements via the Patient Health Questionnaire-9 (PHQ-9) between 2005 and 2018 in the prospective cohort study. PHQ-9 scores greater than 10 indicated depression — scores of 10 to 14 and scores of 15 or greater revealed moderate and moderate to severe depression, respectively. The team evaluated the prevalence of depression and the variables predicting it, and used the National Death Index to determine mortality among the cohort.

A total of 11.6% of study participants had depression, according to the report. Individuals with depression were more likely to have overweight, have less education, smoke, and have a history of stroke compared with those without depression (P <0.05 for all).

The prevalence of depression remained consistent throughout the study, the report shows. Individuals aged 60 years or older had a significantly lower risk of depression compared with participants aged younger than 60 years (adjusted odds ratio [aOR], 0.77; 95% CI, 0.59-1.00). Education level also affected depression risk. Individuals who graduated college and participants who graduated high school experienced a reduced depression risk compared with patients who did not graduate high school (aOR, 0.62; 95% CI, 0.48-0.79 and aOR, 0.33; 95% CI, 0.21-0.51, respectively). Female sex (aOR, 2.02; 95% CI, 1.59-2.56), a body mass index (BMI) of 30 kg/m² or greater (aOR, 1.92; 95% CI, 1.33-2.76), and smoking status indicating current smoking (aOR, 2.41; 95% CI, 1.86-3.11) increased depression risk.

During a 78.2-month follow-up period, 1161 all-cause deaths occurred and 323 were cardiovascular in nature. Depression was associated with an increased risk of all-cause death (adjusted hazard ratio [aHR], 1.36; 95% CI, 1.09-1.70), and moderately severe to severe depression elevated this risk (aHR, 1.67; 95% CI, 1.19-2.34). However, depression was not associated with cardiovascular mortality, according to the report.

A subgroup analysis revealed a significant association between total depression and all-cause mortality among men (aHR, 1.46; 95% CI, 1.08-1.98) and individuals aged 60 years or older (aHR, 1.35; 95% CI, 1.02-1.78), the report shows.

“[H]ealthcare providers should consider incorporating depression screening and management into routine care, especially for subgroups with specific risk factors, due to the increased risk of all-cause mortality in T2DM patients with depression,” according to the study authors.

Study limitations include self-reported demographic and PHQ-9 questionnaire data and an inability to account for confounders, which include family history of depression and diabetes, glycemic control, diabetes duration, and medication use.