Associations Between Glycemic Control, Depressed Mood, Clinical Depression, and Diabetes Distress Before and After Insulin Initiation: An Exploratory, Post Hoc Analysis

INTRODUCTION Although depression is often associated with poor glycemic control in patients with type 2 diabetes mellitus (T2DM), this observation has been inconsistent. This exploratory, post hoc analysis investigated associations between depression parameters and glycemic control using data from a 24-month, prospective, observational, non-interventional study evaluating glycemic response following insulin initiation for T2DM. METHODS We analyzed data from a 24-month, prospective, observational study that evaluated glycemic response in patients with T2DM who initiated insulin therapy (N = 985) in 5 European countries. Secondary measures included patient-reported diagnosis of depression at baseline, severity of depressed/anxious mood (EuroQol (EQ)-5D item) and diabetes-related distress (Psychological Distress domain of the Diabetes Health Profile, DHP-18). The latter two measures were assessed at baseline and 5 time points throughout the study. Glycemic control was measured by glycated hemoglobin (HbA1c) at these same time points. Analyses employed t tests to assess the unadjusted baseline difference in HbA1c between patients with and without the respective depression parameter. The potential effect of demographic and clinical confounding variables was controlled through a linear model structure. Patient HbA1c levels were analyzed by presence/absence of a history of diagnosed depression, depressed mood, and diabetes-related distress. RESULTS Patients with higher depression parameters or distress at baseline had significantly higher rates of microvascular complications at baseline. Patients with a history of diagnosed depression or high diabetes-related distress had higher HbA1c than patients without. HbA1c of patients with or without depressed mood was not significantly different at baseline. The proportion of patients with depressed mood declined after insulin initiation, whereas the proportion of patients with high diabetes-related distress did not significantly change. HbA1c improved following insulin initiation, regardless of presence/absence of studied depression/distress parameters at baseline. CONCLUSION History of diagnosed depression, diabetes-related distress, and depressed mood were associated with a higher rate of microvascular complications. Diagnosed depression and diabetes-related distress also showed higher HbA1c at baseline when insulin was initiated. Insulin therapy improved glycemic control, while preexisting depressed mood declined and diabetes-related distress remained unchanged.