Olanzapine Associated With Disturbance in Glucose homeostasis, development of insulin resistance: Study
Researchers have found in a new study that use of Olanzapine is associated with modest but significant increases in fasting blood glucose and insulin levels, suggesting early impairment of glucose homeostasis and a potential risk of developing insulin resistance. The effects of olanzapine on HbA1c remain inconclusive. These findings highlight the importance of routine metabolic monitoring, including glucose and insulin measurements, early lifestyle interventions, and consideration of preventive pharmacologic strategies in high-risk patients.
Proactive metabolic surveillance and individualized risk assessment are essential to reduce the risk of progression to diabetes in patients receiving olanzapine. The study was published in the Diabetology & Metabolic Syndrome journal by Ridong Y. and colleagues. For the purposes of generating a definitive quantitative evaluation of the metabolic profile associated with olanzapine, the researchers carried out a systematic review involving a complete and thorough search of global biomedical literature through databases such as PubMed/MEDLINE, Scopus, Web of Science, and Embase from the very start until July 1, 2025.
Specifically, only randomized controlled trials performed either in a double-blind or open-label fashion comparing olanzapine with either a placebo or a no-drug control was selected in accordance with strict criteria, and, most importantly, the requirement for pre- and post-treatment measurements of metabolic parameters was imposed to ensure data validity. Data quality in included trials was assessed independently by the Cochrane Risk of Bias 2 tool, while the GRADE approach was employed to evaluate the certainty of pooled evidence. The calculations were done using random-effects models in order to obtain weighted mean differences (WMDs) along with 95% confidence intervals (CIs).
Key findings:
- Independent association between olanzapine treatment and statistically significant increase in fasting plasma glucose concentration, resulting in pooled weighted mean difference value of 2.618 mg/dL (95% CI: 0.283 to 4.954 mg/dL).
- The most significant rise in levels of resting insulin was seen with olanzapine administration, resulting in weighted mean difference of 3.636 µIU/mL (95% CI: 1.964 to 5.307 µIU/mL).
- Unlike fasting values, glycated hemoglobin concentration showed statistically insignificant changes during the short term of observation, having obtained weighted mean difference value of −0.029% (95% CI: −0.284% to 0.226%).
- Subgroup analysis indicated that there is a tendency to greater glycemic injury among patients who received clinically relevant dosages of 10 mg/day and more.
- Prolonged duration of treatment (12 weeks or more) had shown tendency to poorer glycemic indices compared to short-term one.
Therefore, it can be concluded that there are significant increases in FBS and insulin levels among users of olanzapine, which signify disruptions in the glucose balance and predisposition to the development of insulin resistance, whereas there are no clear results about the impact of this drug on HbA1c. This implies that regular checkups of glucose and insulin levels along with the introduction of proper measures is necessary in order to avoid developing diabetes. The randomized study conducted provides an invaluable evidence base for the field of modern clinical psychiatry.
Reference:
You, R., Safargar, M., Prabahar, K. et al. The effect of olanzapine on diabetes related index in humans: a systematic review and meta-analysis of randomized controlled trials. Diabetol Metab Syndr (2026). https://doi.org/10.1186/s13098-026-02223-y
