HbA1c variability linked to depression in elderly

Variability in glycemic control as measured by HbA1c was associated with more depressive symptoms among elderly patients with type 2 diabetes, according to the results of a study published in Diabetes Care.

“The results of the study demonstrate that variability in HbA1c over time (mean 8.7 years) is associated with the subsequent number of depressive symptoms in elderly subjects with type 2 diabetes,” researcher Ramit Ravona-Springer, MD, head of the Memory and Geriatric Psychiatry Clinic at the Sheba Medical Center in Tel Hashomer, Israel, told Medical Economics. “Surprisingly, mean HbA1c levels were not associated with subsequent number of depressive symptoms, suggesting that not all measures of glycemic control over time are effective in prediction of depressive symptoms.

According to Ravona-Springer, depression and diabetes are both highly prevalent in the elderly and the risk for depression is doubled in the presence of diabetes.

“Treatment guidelines for depression or its prevention are lacking in the context of diabetes in the older and growing segment of the population,” she said. “Since better glycemic control is associated with decreased risk for some diabetes- related complications, we aimed to analyze the relationship of glycemic control and depressive symptoms in a cohort of elderly patients with type 2 diabetes.”

Next: Study details

The study included 837 participants from the Israel Diabetes and Cognitive Decline study, which examined the relationship of characteristics of long-term type 2 diabetes with cognitive decline. The researchers assessed symptoms of depression using the 15-item version of the Geriatric Depression Scale (GDS). The mean age of patients was 72.74 years.

The mean score on the GDS was 2.16. One-tenth of participants had a GDS score of 6 of greater, which was the cutoff for clinically significant depression.

Mean HbA1c was significantly correlated with the standard deviation of HbA1c measurement (P<.0001). The standard deviation, but not the average, of HbA1c measurements was significantly associated with the number of depressive symptoms reported.

Finally, for every 1% additional increase in HbA1c standard deviation, the number of depressive symptoms reported increase by a factor of 1.31 (P=.03).

“We also looked for reverse causality, that is, whether depression diagnosis or use of antidepressant medications at the time of entry into the diabetes registry were associated with impaired glycemic control thereafter,” Ravona-Springer said. “Such a relationship was not detected, possibly suggesting that lack of glycemic control leads to depressive symptoms rather than the opposite direction.”

Based on these results, Ravona-Springer said that good and steady glycemic control may be associated with prevention of depressive symptoms in elderly people with type 2 diabetes.