To study the effectiveness of sertraline (Zoloft) in treating depression in adults with diabetes. The study will also determine whether depressed diabetic patients who have successfully responded to sertraline (Zoloft) are more likely to have depression recur if the sertraline (Zoloft) is discontinued.

Part A: Prevention of Depression Recurrence in Diabetes

1. To determine the efficacy of maintenance antidepressant medication in preventing or delaying recur-rence of major depression in diabetes.
2. To determine the relationship of sustained depression remission to social, occupational, and global func-tioning, and to quality of life and compliance with diabetes treatment.
3. To determine clinical features predictive of depression recurrence in diabetes.

Part B. Longitudinal Study of the Interrelationship of Glycemic Control and Depression

1. To determine the effects of depression remission and recurrence on glycemic control.
2. To determine the efficacy of maintenance antidepressant medication in producing sustained benefits in glycemic control.
3. To determine the interrelationship of daily mood with blood glucose and the effect of maintenance treatment on this relationship.

Inclusion Criteria:

• 18-80
• Type 1 or Type 2 Diabetes
• Screen positive for depression

Exclusion Criteria:

• Are pregnant or lactating
• Are known to be hypersensitive to the drug
• Have a recent history of myocardial infarction or unstable heart disease
• Have severe hepatic disease or renal impairment (serum creatinine > 3 mg/dl)
• The subset of patients with psychiatric disorders thought to affect management (e.g., schizophrenia, alcohol and drug dependence) will also be excluded from participation