Up to 20 percent of patients with diabetes have a major depressive disorder. Depression in patients with diabetes may be associated with poor compliance with therapy, poor glycemic control and an increased risk of complications. An important question is whether antidepressant therapy improves diabetes control. Lustman and associates assessed the efficacy of fluoxetine in the treatment of depression in patients with diabetes.

The 60 patients in the double-blind placebo-controlled study were 21 to 65 years of age and met the diagnostic criteria for major depression. Each had a score of 14 or greater on the Beck Depression Inventory (BDI) or the Hamilton Rating Scale for Depression (HAMD). Patients were randomly assigned to receive fluoxetine, which was initiated at a dosage of 20 mg per day and increased up to 40 mg daily as required by the clinical response. Depression and glycemic control were evaluated during the third, fifth and eighth weeks of treatment.

Fifty-four of the 60 patients (27 in each group) completed the study. Treatment and placebo groups were comparable with respect to median age (45.0 and 47.7 years, respectively), mean glycosylated hemoglobin (HbA_1c) level at baseline (8.4 and 8.6 percent, respectively) and duration of diabetes (12.2 and 14.1 years, respectively). Patients were equally distributed among those with type 1 (formerly known as insulin-dependent) and type 2 (formerly known as non–insulin-dependent) diabetes.

After eight weeks of fluoxetine therapy, mean BDI and HAMD scores had dropped significantly, from a mean BDI score of 23.6 to 9.6 and from a mean HAMD score of 20.1 to 9.4. In the placebo group, the mean BDI scores were 22.4 and 13.6 at baseline and after treatment, respectively, and the mean HAMD scores were 19.5 and 14.3 at baseline and after treatment.

Improvement in HbA_1c level was greater in the fluoxetine group than in the placebo group, but the difference was not statistically significant. The mean decrease in HbA_1c was 0.40 percent in the fluoxetine group and 0.07 percent in the placebo group.

The authors conclude that fluoxetine is superior to placebo in the treatment of major depression in patients with diabetes. The trend toward greater improvement in glycemic control in these patients could not be attributed to the effects of treatment on weight or depression. While the long-term benefits of fluoxetine on glycemic control are unclear, the results of this study are promising. Identification and treatment of depression in patients with diabetes will likely improve their quality of life and clinical outcomes.