Association between depression and concurrent Type 2 diabetes outcomes varies by diabetes regimen.
OBJECTIVE
Although depression has weak associations with several Type 2 diabetes mellitus (DM) outcomes, it is possible that these associations are concentrated within certain patient subgroups that are more vulnerable to their effects. This study tested the hypothesis that depression is related to glycaemic control and diabetes-related quality of life (DQOL) in patients who are prescribed injected insulin, but not those on oral glucose-lowering agents alone.


METHODS
Participants (103 on insulin, 155 on oral glucose-lowering agents alone) with Type 2 DM were recruited from a large US healthcare system and underwent assessment of glycaemic control (glycated haemoglobin; HbA(1c)), medication adherence and diabetes self-care behaviours, DQOL and depression (none, mild, moderate/severe).


RESULTS
There was a significant regimen x depression interaction on HbA(1c) (P = 0.002), such that depression was associated with HbA(1c) in patients using insulin (beta = 0.35, P < 0.001) but not in patients using oral agents alone (beta = -0.08, P = NS). There was a similar interaction when quality of life was analysed as an outcome (P = 0.002). Neither effect was mediated by regimen adherence.


CONCLUSIONS
The generally weak association between depression and glycaemic control is concentrated among patients who are prescribed insulin. Similarly, the association between depression and illness quality of life is strongest in patients prescribed insulin. Because this is not attributable to depression-related adherence problems, psychophysiological mechanisms unique to this group ought to be carefully investigated. Clinicians might be especially vigilant for depression in Type 2 DM patients who use insulin and consider its potential impact upon their illness course.
Aikens
J E
JE
Department of Family Medicine, University of Michigan, Ann Arbor, MI 48104-1213, USA. aikensj@umich.edu
Perkins
D W
DW
Piette
J D
JD
Lipton
B
B
D001786:Blood Glucose / Q000378:metabolism; D015190:Blood Glucose Self-Monitoring / Q000523:psychology / Q000592:standards; D003863:Depression / Q000209:etiology* / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000523:psychology*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000627:therapeutic use*; D008297:Male; D055118:Medication Adherence / Q000523:psychology*; D008875:Middle Aged; D011788:Quality of Life; D012648:Self Care; D016903:Drug Monitoring
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin