Is Ignorance Bliss? Depression, Antidepressants, and the Diagnosis of Prediabetes and Type 2 Diabetes

Objective: To examine the association between clinically identified and undiagnosed prediabetes and Type 2 diabetes with depression and antidepressant medication use. Methods: Data come from the National Health and Nutrition Examination Study (2005 and 2007), a population-based cross-sectional survey. Analysis is limited to adults aged 30 and older (n = 3,183, Mean age = 52.1 year). Depression syndrome was measured by the Patient Health Questionnaire-9. Participants were categorized using fasting glucose levels as normoglycemic (glucose <100 mg/dL), undiagnosed prediabetes (glucose 100-125.9), clinically identified prediabetes (glucose 100-125.9 plus clinician diagnosis), undiagnosed Type 2 diabetes (glucose >126), and clinically identified Type 2 diabetes (glucose >126 plus clinician diagnosis or use of antidiabetic medications). Health behaviors included smoking, poor diet, excessive alcohol use, and obesity. Health promotion behaviors included efforts to change diet, lose weight, and increase physical activity. Results: Clinically identified diabetes was associated with 4.3-fold greater odds of depression, but undiagnosed diabetes was not significantly associated with depression. This relationship was more pronounced for prediabetes. Clinically identified diabetes was associated with 1.8-fold greater odds of antidepressant use, but undiagnosed diabetes was not significantly associated with antidepressant use. Health behaviors were not consistently related to depression syndrome. Conclusion: The relationship between diabetes status and depression and antidepressant use depends on whether the diabetes has been clinically identified. Findings are consistent with the hypothesis that the relationship between diabetes and depression may be attributable to factors related to disease management. Previous reports linking antidepressants and diabetes may be attributable to clinical ascertainment bias.