Psychiatric Morbidity in Women With Previous Gestational Diabetes Mellitus: A Nationwide Register-Based Cohort Study

OBJECTIVE To investigate associations between previous gestational diabetes mellitus (GDM) and incident psychiatric morbidity, and to explore the role of subsequent diabetes development in psychiatric morbidity risk. RESEARCH DESIGN AND METHODS A nationwide register-based cohort study including all women delivering in Denmark from 1997 to 2018 was conducted. GDM exposure was based on diagnosis code, whereas psychiatric morbidity outcome was based on diagnosis code and psychopharmacological medication use. Multiple Cox regression and mediation analyses were performed. RESULTS In a study population of 660,017 women, previous GDM was associated with increased risk of depression based on diagnosis code and/or medication use (adjusted hazard ratio [aHR] 1.22 [95% CI 1.18–1.27]), any psychiatric diagnosis (aHR 1.20 [95% CI 1.13–1.27]), and any psychopharmacological medication use (aHR 1.21 [95% CI 1.17–1.25]). Moreover, risk of depressive and anxiety disorders, as well as antidepressant and antipsychotic medication use, was increased, with aHRs ranging from 1.14 (95% CI 1.05–1.25) to 1.32 (95% CI 1.22–1.42). No associations were found regarding substance use disorders, psychotic disorders, bipolar disorders, postpartum psychiatric disease, or anxiolytic medication use. Psychiatric morbidity risk was higher in women with versus without subsequent diabetes development. However, GDM history affected risk estimates only in women without subsequent diabetes. Subsequent diabetes mediated 35–42% of the associations between GDM and psychiatric morbidity. CONCLUSIONS GDM was associated with increased psychiatric morbidity risk. Subsequent diabetes development played a significant role in future psychiatric morbidity risk after GDM, although it only partly explained the association.