A Systematic Review of Long-term Antidepressant Outcomes in Comorbid Depression and Type 2 Diabetes

Background Depression is a common and chronic comorbidity affecting approximately one in four people with type 2 diabetes (T2DM), and often lasting several years. Past systematic reviews have been unable to identify evidence for long-term (12+ months) antidepressant treatment outcomes in comorbid depression and type 2 diabetes. These reviews are >10years old, included only randomised controlled trials or had limited search strategies. We aimed to systematically review observational studies for long-term outcomes of antidepressant treatment in adults with comorbid depression and T2DM, including broader, up-to-date searches. Methods and findings This review was pre-registered on PROSPERO (CRD42020182788). We searched seven databases using terms related to depression, T2DM and antidepressant medication. From 14,389 reports retrieved, 63 were screened at full text stage and 0 met inclusion criteria. The reasons for exclusion at full text stage were: Studies did not meet inclusion criteria for antidepressant treatment (n = 50); studies did not meet inclusion criteria for T2DM (n = 36); studies did not meet inclusion criteria for depression (n = 29); studies did not include follow-up time (n = 25); studies did not meet inclusion criteria for observational study (n = 14); studies did not include any measurable outcomes (n = 5); studies did not include a suitable comparison (n = 3). Conclusions We found no evidence concerning long-term outcomes of antidepressant treatment in individuals with comorbid depression and T2DM. Insufficient ascertainment of antidepressant prescription, case identification, and short follow-up times are the primary reasons for this. Research is urgently required to determine long-term outcomes associated with antidepressant treatment in this patient group.