Longitudinal analysis of depressive symptoms and glycemic control in type 2 diabetes.
OBJECTIVE
To compare whether depressive symptoms are more strongly related to subsequent or prior glycemic control in type 2 diabetes and to test whether patient characteristics modify these longitudinal associations.


METHODS
On two occasions separated by 6 months, depressive symptoms and glycemic control were assessed in 253 adults with type 2 diabetes. Regression analyses examined depressive symptoms as both a predictor and outcome of glycemic control and tested whether medication regimen (e.g., insulin versus oral drugs) was an effect modifier before and after adjusting for baseline levels of the outcome being predicted.


RESULTS
Depressive symptom severity predicted poor glycemic control 6 months later (P = 0.018) but not after baseline glycemic control was taken into account (P = 0.361). Although baseline glycemic control did not generally predict depressive symptoms 6 months later (P = 0.558), it significantly interacted with regimen (P = 0.008). Specifically, glycemic control predicted depressive symptoms among patients prescribed insulin (beta = 0.31, P = 0.002) but not among those prescribed oral medication alone (beta = -0.10, P = 0.210). Classifying depression dichotomously produced similar but weaker findings.


CONCLUSIONS
Depressive symptoms do not necessarily lead to worsened glycemic control. In contrast, insulin-treated patients in poor glycemic control are at moderate risk for worsening of depressive symptoms. These patients should be carefully monitored to determine whether depression treatment should be initiated or intensified.
Aikens
James E
JE
Department of Family Medicine, University of Michigan, Ann Arbor, Michigan, USA. aikensj@umich.edu
Perkins
Denise White
DW
Lipton
Bonnie
B
Piette
John D
JD
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D003863:Depression / Q000453:epidemiology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000523:psychology*; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D012044:Regression Analysis; D015203:Reproducibility of Results; D016896:Treatment Outcome
D001786:Blood Glucose; D006442:Glycated Hemoglobin