Depression and hemoglobin A1c in type 1 and type 2 diabetes: The role of self-efficacy

Aims: To examine a self-efficacy explanation of the finding that depression is related to hemoglobin A1c (A1c) level in people with type 1 but not type 2 diabetes. Methods: Cross-sectional design involving 124 participants with type 1 (n = 32) and type 2 (n = 92) diabetes. Participants completed measures of depression and diabetes-related self-efficacy. A1c was obtained from medical records. Results: Replicating prior findings, A1c was significantly correlated with depression in type 1 participants (r = .51, p < .01), but not in type 2 participants (r = .11, ns). As hypothesized, A1c was significantly correlated with self-efficacy among type 1 participants (r = -.42, p < .05) but not among type 2 participants (r = -.01, ns). Self-efficacy also mediated the effect of A1c on depression among the type 1 participants (Z = 2.21, p < .05). Conclusion: In people with type 1, but not type 2 diabetes, A1c levels are related to diabetes adherence mastery (self-efficacy), which mediates the link between A1c and depression. Results are discussed with regard to the proposal that perceptions of ineffective control over one's health play a role in the development of depression (a consequence model of depression in diabetes). (C) 2010 Elsevier Ireland Ltd. All rights reserved.