Background: Depression and diabetes have been recognized as major public health issues in China, however, no studies to date examined the factors associated with the development of depression in patients with diabetes in China. This study aimed to estimate the prevalence of co-morbid depression among adults with type 2 diabetes mellitus (DM) and to examine the influence factors of co-morbid depression in a group of patients with type 2 DM.

Methods: The study was conducted from March l to May 31, 2012, in the Department of Endocrinology of the First Affiliated Hospital of the General Hospital of the People's Liberation Army (PLA). A systematic random sample of 412 type 2 DM patients aged over 18 years was selected. A structured questionnaire was used for collecting the information about socio-demographic data, lifestyle factors and clinical characteristics. Depression and social support was evaluated by using the Chinese version of Beck Depression Inventory (BDI) and Social Support Rate Scale (SSRS), respectively. Weights and heights were measured. Hemoglobin A1c (HbA1c) was abstracted from each patient directly after the interview.

Results: Of the total sample, 142 patients had depression according to the BDI scores (BDI scores ≥14), the prevalence of co-morbid depression in this study population was 5.7 % (142/2500). Of which, 56 had major depression (BDI ≥ 21), and 86 had moderate depression (BDI ≥ 14&BDI < 21). Logistic regression analysis indicated that a high HbA1c level, a high BMI, low quality health insurance, and being single, were significantly associated with the development of depression. However, a family history of diabetes and a high social support level are likely protective factors.

Conclusions: The prevalence of co-morbid depression was 5.7 % among Chinese subjects with type 2 DM in this study. High HbA1c level, high BMI score, being single, low social support level, and low quality health insurance were associated with the presence of depression. These findings support a recommendation for routine screening and management in China for depression in patients with diabetes, especially for those in primary care, to reduce the number of the depressed or the misrecognized depressed diabetic patients.