The effect of olanzapine on diabetes related index in humans: a systematic review and meta-analysis of randomized controlled trials
Abstract
Background and aim: Olanzapine is a widely used second-generation antipsychotic with well-established efficacy in the treatment of schizophrenia, bipolar disorder, and related psychiatric conditions. However, its use has been consistently linked to metabolic adverse effects, particularly disturbances in glucose regulation. This systematic review and meta-analysis aimed to quantitatively evaluate the effects of olanzapine on key diabetes-related biomarkers, fasting blood sugar (FBS), fasting insulin, and glycated hemoglobin (HbA1c), in human populations, using evidence derived exclusively from randomized controlled trials (RCTs).
Methods: A comprehensive literature search was conducted in PubMed/MEDLINE, Scopus, Web of Science, and Embase from inception to July 1, 2025, without language or date restrictions. Eligible studies were RCTs involving human participants that compared olanzapine with placebo or no treatment and reported pre- and post-intervention data for FBS, fasting insulin, or HbA1c. Study quality was assessed using the Cochrane Risk of Bias 2 tool, and the certainty of evidence was evaluated using the GRADE framework. Pooled effect estimates were calculated as weighted mean differences (WMDs) with 95% confidence intervals (CIs) using random-effects models. Subgroup, sensitivity, and publication bias analyses were performed to explore heterogeneity and assess result robustness.
Results: Fifteen RCTs comprising 18 comparison arms were included in the meta-analysis.…
How strong is the evidence?
Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid.
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