to examine the longitudinal effect of depression on glycemic control in a sample of patients with type 2 diabetes.

the patients were recruited from diabetes clinic in Saudi airlines medical center, in Jeddah, the base line study community consisted from 172 patients with type 2 diabetes. They were assessed for depression using BDI II, and diagnostic interview, and for diabetic control using HbA1c. We created a person-period data set for each patient to cover 6 months intervals up to 3 years. We used generalized estimation equation (GEE) for analysis of longitudinal data. HbA1C was the response variable while depression and time were the main covariates. Variables were included in GEE models based on clinical importance and preliminary analysis. Other variables included as covariates were gender, education, duration of diabetes, co-morbidity and LDL. All statistical analysis used α = 0.05 level of significance and were performed using SPSS software version 21.

Unadjusted HbA1c means were significantly higher in depressed vs. non-depressed subjects at all time points. The adjusted HbA1c means in final GEE model were significantly higher in depressed vs. non-depressed subjects. In all adjusted models depression was a predictor of glycemic control weather it was BDI score (estimate = .049, P = .002), diagnoses of MDD (estimate = 2.038, P = .000), or other depressive diagnosis (estimate = 1.245, P = .000).

This study on clinical sample of type 2 diabetic patients demonstrates that there is a significant longitudinal relationship between depression and glycemic control and that depression is associated with persistently higher HbA1c over time.

The authors have not supplied their declaration of competing interest.