Depression, diabetes, and glycemic control in an American Indian community.

Depression has been associated with diabetes1 and poor glycemic control2 in previous reports. There are also significant health care costs associated with depression in diabetes.3,4 Most published reports as well as a recent meta-analysis have shown that depression is more common in individuals with diabetes than in those without diabetes.1,5,6 Several prospective studies have shown that individuals with depression were approximately twice as likely to develop type 2 diabetes than those who were not depressed,7–11 suggesting that depression is itself related to development of diabetes. One of these studies suggests that this association may be mediated through changes in central adiposity,9 although another study reported that depression predicted development of diabetes independent of central adiposity.11 Depression has also been associated with hyperglycemia,2 diabetic complications,12 and increased mortality13 in individuals with diabetes. The relationship between depression and diabetes may be complicated by sociodemographic factors, such as education, race, ethnicity, social support, socioeconomic status, and access to health care. One recent study of a national sample reported that depression predicted the development of future diabetes in individuals with low education levels, but not in those with high education levels.14 The relationship of depression and diabetes has not been well studied in ethnic minority groups.15 Although previous reports have generally shown that depression is more common among individuals with diabetes than among those without diabetes, this association was not found in some recent studies of ethnic minority groups. In 3 studies including Hispanic participants16–18 and in a study of a multiethnic sample,19 depression was not associated with diabetes. However, consistent with previous reports, a recent study in Hispanic individuals with diabetes showed that hyperglycemia was associated with depression.20 The relationship between depression and diabetes, therefore, may vary by ethnic group. Further studies of depression and diabetes in ethnic minority communities are important because diabetes represents a significant health burden in these populations.21,22 Psychiatric diagnoses that might co-occur with either diabetes or risk factors for diabetic complications, such as hyperglycemia warrant careful examination. Not only is there a disparity in the prevalence of diabetes between whites and ethnic minority groups,22 but there may also be disparities in depression treatment. Recent studies have shown that Hispanics and African-Americans with diabetes were less likely to receive depression treatment than whites.19,20,23 There have been few published reports on the relationship between depression and diabetes in American Indians. One recent study reported that a past diagnosis of depression (although not a current depression diagnosis) was associated with current diagnosis of diabetes in 2 American Indian reservation populations.24 In another report including people with diabetes from the national Behavioral Risk Factor Surveillance System (BRFSS), the prevalence of mental health rated “not good” was significantly higher among American Indians than among whites.25 Both of these studies relied on self-report for diagnosis of diabetes, and neither report assessed markers for metabolic risk such as glycosylated hemoglobin (HbA1c) and cholesterol. Authors of both reports call for further studies on the association between diabetes and psychiatric disorders in American Indian populations. The prevalence of diabetes among American Indians has increased substantially in recent years and is a significant public health issue.26 American Indians, along with other ethnic minority groups in the United States, have a higher prevalence of diabetes and diabetic complications than whites.22 For this reason, it is clinically important to identify possible psychiatric diagnoses, such as depression, that might co-occur with diabetes and diabetic complications in American Indians. The Pima Indians in particular have a very high prevalence of type 2 diabetes.27 In this study, we compared the prevalence of depression in Pima Indians with and without diabetes as diagnosed according to the 1997 American Diabetes Association criteria.28 We also examined whether depression was associated with markers of metabolic risk such as HbA1c and cholesterol in subjects with and without diabetes. Results from the pilot phase of this study, in which depression was assessed in face-to-face interviews with 541 persons, were published previously.29 In the current report, depression was determined using a self-administered questionnaire. We report a large population-based study of depression and diabetes among American Indians in the United States.