Both diabetes and depression during or after pregnancy adversely affect maternal and child outcomes.  Although guidelines address the management of mothers with either diabetes or depression, less is known about mothers who have both conditions.  We systematically reviewed the literature to assess the prevalence and management of women who have both diabetes and perinatal depression.  PubMed/MEDLINE and EMBASE were searched (28 October 2014) using terms related to diabetes, depression, and pregnancy (no language or date limits); 1,008 unique articles were identified.  A total of 32 articles (including 2 from bibliographies) describing women with diabetes during pregnancy who also had depression or depressive symptoms before, during, or after pregnancy were included.  Of these, 18 articles included women with gestational diabetes, 1 included women with type 1 diabetes, and 13 included women with any type of diabetes.  Most studies were observational (prospective or retrospective).  Sample sizes ranged from 36 to >32 million (database study).  The prevalence of coincident diabetes (any type) and depression in pregnant women ranged from 0.06% to 1.6% (median 0.41%).  The prevalence of depression among pregnant women with diabetes ranged from 4.5% to 56.7% (median 19%).  Most articles examined whether pregnant women with diabetes were more likely to have perinatal depression than women without diabetes.  However, there was no consensus: 7 articles reported a significant association between diabetes and perinatal depression, 10 articles reported no association, and 1 article was inconclusive.  This lack of consensus is likely related to heterogeneity between studies, including different definitions of perinatal depression and the timing of assessment.  Importantly, we found no guidance on the treatment or management of pregnant women with both diabetes and depression.  Given the increasing prevalence of diabetes and depression, specific guidance for the care of pregnant women with both conditions is warranted.  Funding: Eli Lilly Australia & New Zealand.