Is alcohol use disorder associated with higher rates of depression and anxiety among people with new onset type 2 diabetes? A cohort study using linked primary care data in England

Introduction Depression and alcohol use disorder (AUD) in people living with Type 2 diabetes mellitus (T2DM) are associated with worse health outcomes. AUD is strongly associated with depression and anxiety, but it is not known how these conditions cluster in people with T2DM. We investigated rates of new episodes of depression and anxiety following T2DM diagnosis in people with and without prior AUD among an English primary care population. Methods The study population was people diagnosed with T2DM between 2004 and 2019. We used the Clinical Practice Research Datalink (CPRD) Aurum database and linked Hospital Episode Statistics Admitted Patient Care (HES APC) and Office for National Statistics (ONS) mortality data. We examined incidence of new episodes of anxiety or depression in people with T2DM with and without AUD. AUD was defined as any of i) clinical diagnosis; ii) alcohol withdrawal; or iii) chronic alcohol-related harm (physical or mental) using SNOMED-CT or ICD-10 codes. People were excluded if they had codes for depression/anxiety 12 months prior to T2DM diagnosis. Poisson regression models were fitted adjusting sequentially for a) age, gender, calendar time; b) region, Index of Multiple Deprivation, ethnicity, body mass index, smoking status, Charlson co-morbidity index; and c) history of a mental health condition. Results Our study population was 479,447 people of whom 10,983 (2.3%) had an AUD code prior to T2DM diagnosis. After adjusting for all measured confounders except history of a mental health condition, IRR for depression was 2.00 (95% CI 1.93, 2.06) for people with AUD compared to without AUD. This reduced to 1.45 (95% CI 1.41, 1.50) after further adjustment for history of a mental health condition. Findings for anxiety were substantially similar to those for depression (adjusted for all measured confounders except history of a mental health condition, IRR 2.08 95% CI 1.99, 2.18 fully adjusted IRR 1.48 95% CI 1.41, 1.55). Conclusions People with AUD have over double the rates of depression and anxiety following T2DM diagnosis than those without AUD. This was only partially explained by pre-existing diagnoses of mental health conditions. A holistic approach incorporating mental health support is needed to improve health outcomes for people with AUD who develop T2DM.