Depressive Symptoms May Be Linked to Risk for Incident Diabetes in Older Adults

April 26, 2007 — Compared with their peers, older adults who report high levels of depressive symptoms — whether these symptoms occur once, increase, or persist — have a higher risk of developing type 2 diabetes, according to results of a 10-year study. The risk for incident diabetes among the study participants, who were part of the Cardiovascular Health Study (CHS), was independent of other risk factors. The study is published in the April 23 issue of the Archives of Internal Medicine.
Lead author Mercedes R. Carnethon, PhD, from Northwestern University in Chicago, Illinois, told Medscape the main finding was that, in addition to older adults who had a single report of high depressive symptoms, those whose depressive symptoms worsened were more likely to develop diabetes, as were those who had persistently high symptoms of depression.
She explained that most previous studies suggesting that depressive symptoms are linked with risk of developing diabetes looked at younger populations and were based on a single self-report of depression and a single measurement of factors related to depression and diabetes. Because of the episodic nature of depressive symptoms, a single self-report might not fully characterize the relationship between depression and diabetes.
The authors aimed to test the hypothesis that high depressive symptoms were linked with incident diabetes in adults 65 years and older by investigating single and multiple reports of depression and repeated measurements of related factors. They write that to their knowledge, theirs is the only study to look at this relationship in older adults, a population known to have a high prevalence of diabetes and depression.
The study population comprised participants in the CHS, a prospective, population-based, cohort study of cardiovascular disease in adults 65 years and older. The 4681 participants in the current study had complete data and no diabetes at baseline. They were examined yearly from baseline (1989 or 1990) to 1999.
At each annual examination, participants filled in a 10-item Center for Epidemiologic Studies–Depression Scale (CES-D) questionnaire, which measures depressive symptoms during the previous week. The questions deal with mood (5 questions), irritability (1 question), calories/energy (2 questions), concentration (1 question), and sleep (1 question). They are scored from 0 (rarely) to 3 (most of the time) for a maximum of 30 points.
The researchers looked at 3 measures of high depressive symptoms: baseline CES-D of 8 or higher (high score), increase in CES-D of 5 points or higher (increasing score), and 2 consecutive CES-D scores of 8 or higher (persistently high score).
The participants' annual examination also included clinical measures of height and weight (used to calculate body mass index), as well as blood tests to determine levels of C-reactive protein and fasting glucose. New-onset diabetes was defined as the initiation of therapy for diabetes or having a high fasting blood glucose level.