Incidence and factors associated with new depressive episodes in adults with newly treated type 2 diabetes: A cohort study

Aims: Several methods are available to help identify people with depression; however, there is little guidance on when to start screening. This study estimated the incidence of new depressive episodes and identified factors associated with onset in adults with newly treated type 2 diabetes.

Methods: Administrative health data from Alberta, Canada was used to identify people starting metformin between April 2011 and March 2015. People with a history of depression before metformin initiation were excluded. Person-time analysis was used to calculate the incidence rate of new depressive episodes over the next 3 years, stratified by sex, age, and year. Multivariable logistic regression was used to identify factors independently associated with a new depressive episode.

Results: 42,694 adults initiated metformin; mean age 56 years, 38 % female. A new depressive episode occurred in 2752 (6 %) individuals, mean time to onset was 1.4 years and overall incidence rate was 22.3/1000 person-years. Factors associated with a new depressive episode were female sex, younger age, previous mental health conditions, frequent healthcare utilization, and multiple comorbid conditions.

Conclusions: Screening for depression should begin within 1-2 years of metformin initiation and focus on females, those < 55 years old, those with a history of mental health conditions, and those with multiple comorbid conditions.