Depression, Diabetes, and Glycemic Control in Pima Indians
- Puneet K. Singh, BA,
- Helen C. Looker, MBBS,
- Robert L. Hanson, MD, MPH,
- Jonathan Krakoff, MD,
- Peter H. Bennett, MB, FRCP and
- William C. Knowler, MD, DRPH
- From the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
- Address correspondence to Helen C. Looker, National Institutes of Health, 1550 E. Indian School Rd., Phoenix, AZ 85014. E-mail:
Few studies have addressed the relationship of depression and diabetes in ethnic minority groups, especially Native Americans (1). We examined the relationship between depression and diabetes in a community-based sample of 541 Pima Indians aged ≥18 years (192 with and 349 without diabetes) examined from September 2002 through February 2003.
Depression was defined by five or more depressive symptoms lasting ≥2 weeks, as assessed with PRIME-MD (Mood Module in the Primary Care Evaluation of Mental Disorders) (2). Diabetes was defined by a glucose tolerance test (fasting plasma glucose ≥7.0 mmol/l or 2-h plasma glucose ≥11.1 mmol/l) or previous clinical diagnosis.
The prevalence of depression was 16.3% (18.7% in women and 12.6% in men, P = 0.06). In both sexes, the prevalence of depression was higher in diabetic individuals (men 17.2 vs. 10.9%, women 20.2 vs. 17.6%), although these differences were not statistically significant (for total sample: age- and sex-adjusted odds ratio 1.3 [95% CI 0.7–2.1]). In diabetic individuals, HbA1c was higher by 1.2% in those with depression (9.3 vs. 8.1%, P < 0.01), although depression was not related to HbA1c in nondiabetic individuals (5.2 vs. 5.3%, P = 0.2). This association remained significant in a multivariate linear regression model that included age, sex, duration of diabetes, and BMI (HbA1c higher by 1.1% in depressed persons, P = 0.01). Fasting plasma glucose was also higher, but not significantly so, in depressed diabetic individuals (10.2 vs. 9.5 mmol/l, P = 0.3).
Although studies of depression in Native-American communities are limited, our findings are consistent with previous suggestions that depression is several times more prevalent among Native Americans than in the general U.S. population (3). Our finding that the prevalence of depression was somewhat higher in diabetic individuals is also consistent with previous studies (1,4–6). Our study lacks precision to estimate the association of depression with diabetes because of the relatively small sample size (541, as compared with 21,513 to 1.3 million in other recent reports [4–6]). The high prevalence of depression in our study suggests that certain social, cultural, or economic factors may overshadow the influence of diabetes on depression in this population.
The higher HbA1c in depressed diabetic individuals is consistent with previous findings in other populations (7). Treatment of depression reportedly improves glycemic control in diabetic patients, although the long-term effects are not known (8,9). This study adds to the sparse literature on depression and diabetes in ethnic minority groups. Identification and treatment of depression may be an important aspect of treating diabetes in Native Americans.
We thank Dr. Richard Rubin, Dr. Patrick Lustman, and Dr. Mary de Groot for advice; Dr. Diane Montella and Priscilla Foote, MSW, of Gila River Health Care; and the members of the Gila River Indian Community for their participation.