30 % of patients with Type 2 diabetes have depression and is associated with higher blood glucose levels with time, new research suggests
A study looking at the longitudinal effects of depression on glycemic control in 11,525 veterans with type 2 diabetes shows that hemoglobin A1c (HbA1c) values are, on average, 0.13% higher in those with depression during a 4-year period.
“Our study shows depression is a major and important comorbidity in people with type 2 diabetes. The fact that the difference persisted over time and that the depressed group had higher mean HbA1c at all 36 time points was surprising,” study coauthor Leonard Egede, MD, MS, from the Medical University of South Carolina in Charleston, said in a statement.
Dr. Egede added that this difference is “quite significant” and is enough to push individuals with diabetes over the optimal threshold for glucose control and increase their risk for poor outcomes.
Comorbid depression occurs in approximately 30% of adults with diabetes and is associated with poor metabolic control, higher complication rates, increased healthcare use and costs, poorer quality of life, and increased disability and mortality rates.
The study authors point out that although there is a great deal of literature reporting the association between depression and diabetes outcomes, to date, none of the research has examined the effects of depression on glycemic control in adults with type 2 diabetes with time.
To address this research gap, investigators created a dataset of adults with type 2 diabetes who received medical care at a Veterans Affairs facility in the Southeastern United States. Study participants had an average age of 66 years. Almost half (48%) were white, 27% were African American, and 25% were of other races. Participants were evaluated at 3-month intervals from 1997 to 2006 for a total of 36 intervals. Of the total group, 6% were diagnosed with depression, and the mean baseline HbA1c level was 7.3%.
The study’s primary outcome was a mean difference in HbA1c levels between depressed and non-depressed subjects with time, and the mean follow-up time was 4.1 years.
“It is noteworthy that this study found a significant association between depression and glycemic control over time even in a sample with relatively well-controlled diabetes. This suggests that in populations with higher baseline HbA1c, the magnitude of association may be much higher,” the study authors write.
Among depressed participants, the change in HbA1c levels did not differ according to race or age.
- In a sample of male veterans with type 2 diabetes, there was a significant longitudinal relationship between depression and glycemic control as measured by HbA1c level. At each time point, depressed subjects had significantly higher unadjusted and adjusted mean HbA1c values vs non-depressed subjects.
- In a sample of male veterans with type 2 diabetes, depression was associated with persistently higher HbA1c levels for an average of 4 years of follow-up. In the final mixed model, depressed subjects had significantly higher adjusted mean HbA1c values with time, and this mean difference was maintained with time.
Gen Hosp Psychiatry. 2008;30:509-514.
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