How common is antidepressant use in people with type 2 diabetes and who is at risk?

Problem

Diabetes is the third most common long-term condition in England after hypertension and depression, and it affects around six percent of the population. People with type 2 diabetes (T2D) appear to be more at risk of developing depression and have poorer outcomes if they are depressed. However estimates of the prevalence of depression in people with type 2 diabetes vary widely, ranging from 0-39%. However, here is very little information on populations within the UK. This study examines antidepressant treatment in people with type 2 diabetes and identify those most at risk.

Approach

This was a retrospective cohort study using data from The Health Improvement Network (THIN) primary care database. THIN contains electronic primary care health records for approximately 12 million patients in the UK. The majority of diabetes and depression is usually treated and managed in primary care hence diagnoses, monitoring and treatments is captured by THIN. We calculated the number of new and prevalent users antidepressant treatment in people with type 2 diabetes compared to the general population. We used a Poisson regression to examine initiation of antidepressant treatment in people with and without type 2 diabetes and the relationship between initiation and gender, age and deprivation (quintiles of Townsend scores).

Findings

There were 466,399 people with a diagnosis of T2D, of which 328,277 (70%) were newly diagnosed between 2000 and 2016. The total follow up time was 1,199,362 years. The hazard ratio for initiation antidepressant medication was 1.18 (95% CI 1.17 to 1.20) in people with type 2 diabetes compared people of similar age and gender, but without type 2 diabetes. Women with type 2 diabetes were about 50% more likely than men to initiate antidepressants (HR 1.53, 95% CI 1.17 to 1.20). Antidepressant treatment in people with type 2 diabetes increased with social deprivation and rates of anti-depressant prescribing were 62% higher in the most deprived quintile (95% CI 1.59 to 1.65) compared to the least deprived. People who were prescribed insulin were 50% more likely to be on antidepressant treatment than individuals not on insulin (HR 1.51 95% CI 1.46 to 1.57).

Consequences

Patients with type 2 diabetes are at increased risk of developing diabetes, but the risks vary by age, gender, treatment and deprivation. Targeting screening at higher risk patients may help clinicians to identify, treat and improve outcomes for patients with comorbid common mental health problems and type 2 diabetes.