Prevalence of depression in Type 1 diabetes and the problem of over-diagnosis

To determine the prevalence of depression and diabetes distress in adults with Type 1 diabetes and the rate of false-positives when compared with rates of major depressive disorder.

The sample consisted of 368 individuals with Type 1 diabetes, aged > 19 years. Individuals completed: the eight-item Patient Health Questionnaire depression scale (PHQ8), which was coded using four scoring criteria (scores > 10, >12 and >15, and Diagnostic and Statistical Manual of Mental Disorders 5 (DSM) algorithm scores); the Type 1 Diabetes Distress Scale; and the Structured Clinical Interview for DSM Disorders (SCID) to assess major depressive disorder.

The prevalence rates of depression according to the eight-item Patient Health Questionnaire were: score >10, 11.4%; score >12, 7.1%; score >15, 3.8%; and positive algorithm result, 4.6%. The prevalence of major depressive disorder was 3.5%; and the prevalence of at least moderate diabetes distress was 42.1%. Depending on the criterion used, the false-positive rate when using the Patient Health Questionnaire compared with the results when using the SCID varied from 52 to 71%. Of those classified as depressed on the PHQ-8 or Structured Clinical Interview for DSM Disorders, between 92.3 and 96.2% also reported elevated diabetes distress. No significant association was found between any group classed as having depression according to the PHQ8 or the SCID and HbA_1c concentration. Depression was significantly associated with more other life stress, more complications and a lower level of education.

We found an unexpectedly low rate of current depression and major depressive disorder in this diverse sample of adults with Type 1 diabetes, and a very high rate of false-positive results using the Patient Health Questionnaire. Considering the high prevalence of diabetes distress, much of what has been considered depression in adults with Type 1 diabetes may be attributed to the emotional distress associated with managing a demanding chronic disease and other life stressors and not necessarily to underlying psychopathology.