Is Second-Generation Antipsychotic Treatment Continuity Associated with New Onset Diabetes Mellitus in Patients with Major Depressive Disorder?

Background: Second-generation antipsychotics (SGAs) have been commonly used in patients with severe mental illness. The possible association of SGA treatment continuity with new onset diabetes mellitus (NODM) in major depressive disorder (MDD) patients is a concern. The aim of this study was to determine if there are differences in the risk of NODM between MDD patients receiving SGAs continuously for more than 8 weeks and MDD patients receiving SGAs irregularly. Methods: From the National Health Insurance Research Database (NHIRD), 859 MDD patients treated with SGAs continuously for more than 8 weeks were analyzed in a 1:1 propensity-score-matched sample to patients treated with SGAs irregularly. Patients were followed up and the outcome was based on ICD-9 CM codes indicating NODM. Cumulative incidences of NODM were calculated and the Cox proportional hazards model with competing risk was used to determine the risk factors for NODM. Results: After propensity-score matching, 55 (6.40%) of 859 patients treated with SGAs continuously for more than 8 weeks and 59 (6.87%) patients treated with SGAs irregularly developed NODM. Rates of NODM among all matched patients were similar. SGA treatment continuity showed no significant risk for NODM (hazard ratio [HR] = 0.677; 95% confidence interval [CI], 0.437-1.047; p value=0.079). However, elevated risk of NODM was associated with increased age (per year) (HR= 1.040; 95% CI, 1.026-1.054; p value <0.001), history of hypertensive disease (HR= 2.506; 95% CI, 1.399-4.488; p value =0.002), and history of hyperlipidemia (HR= 2.956; 95% CI, 1.782-4.905; p value <0.001). Conclusions: SGA treatment continuity is not associated with significant risk of NODM in MDD patients. The results of this study are helpful for weighing the potential benefits against the potential side effects and treatment effects of SGAs in treatment-resistant depression.