A prospective study of Type 2 diabetes and depressive symptoms in the elderly: The Rancho Bernardo Study

Aims The association between Type 2 diabetes and depressive symptoms was examined prospectively to assess possible causal relationships between the two diseases. Methods A cohort of 971 men and women aged 50 and older from the adult population of Rancho Bernardo, California had an oral glucose tolerance test and completed the Beck Depression Inventory (BDI) at two clinic visits, 1984-87 and 1992-96. Results Depressive symptoms at baseline were associated with higher follow-up levels of non-fasting plasma glucose (P = 0.001) and an increased risk of developing Type 2 diabetes [odds ratio (OR) = 2.50; 95% confidence interval (CI) = 1.29-4.87], independent of sex, age, exercise and body mass index. Conversely, baseline non-fasting plasma glucose was not significantly associated with follow-up depressive symptoms and Type 2 diabetes at baseline was not significantly associated with the onset of BDI scores greater than or equal to 11 by the second visit (OR = 0.73; 95% CI = 0.41-1.30). Conclusions Depressed mood is more likely to be a risk factor for Type 2 diabetes in older adults than the reverse.