The aim of the present study was to identify and describe longitudinal patterns of depression in a community sample of people with type 2 diabetes in Quebec, Canada.
A prospective community based study in Quebec, Canada, was carried out between 2008 and 2011. Participants with diabetes were assessed at baseline and at 1, 2 and 3 years follow-up (n=1388). Depression was assessed using the patient health questionnaire (PHQ-9).
Longitudinal latent class analysis yielded four clusters representing different longitudinal patterns of depression: cluster 1 ("no depression"; 67%): participants had neither minor nor major depression over time. Cluster 2 ("slowly increasing prevalence of minor and major depression over time"; 20%): participants had low levels of depression at baseline but increasing levels of minor and major depression over time; while most of the Cluster 3 ("increasing major depression"; 6%) participants had high and increasing levels of major depression over time. Participants in cluster 4 ("improved depression"; 7%) started with high levels of depression but progressed to low levels of depression.
Our results provide important evidence of different longitudinal patterns of depression in people with type 2 diabetes. Identification of four distinct groups of participants might improve our understanding of the course of depression and may provide a basis of classification for intervention.