Depression leads to higher Hemoglobin A1c values in adolescents with Diabetes Type 1. Poor blood glucose monitoring is also associated with poor glycemic control and higher Hemoglobin A1c values.
Here’s a review article on the relationship between depression and higher Hemoglobin A1c findings in teens with Diabetes Type 1: http://www.medscape.com/viewarticle/703095?src=rss . The original article is in Diabetes Care 2009;32:804-806.
From my perspective, depression is a multisystemic illness with multi-component pathophysiology. One frequent problem is excessive norepinephrine signaling. Another is suboptimal thyroid hormone signaling (reflecting hypothalamic-pituitary-thyroid axis dysregulation in depression). These two conditions may increase insulin resistance, resulting in higher hemoglobin A1c values, depending on the other pathophysiologic components of depression (e.g. hypothalamic-pituitary-adrenal axis dysregulation coupled with trauma or severe stresses results in impaired gluconeogenesis and lower blood sugar).
Thus the study findings are not unexpected.
The conclusion of the study is that patients should be monitored and treated for depression since this would improve the patient’s capacity for participating in glycemic control. From my perspective, this would also help treat the pathophysiology which underlie both depression and diabetes, thus further improving glycemic control.