Insulin Resistance in Antipsychotic-Naive Patients – A Case–Control Study

Background: Patients with psychosis experience increased premature mortality compared to the general population. Higher suicide rates, poor nutrition, neglect of physical health, and a higher prevalence of type 2 diabetes mellitus are some of the notable causes for reduced lifespan. The abnormal glucose metabolism frequently seen in these individuals is often attributed to the use of antipsychotics. However, an emerging hypothesis suggests that patients with psychosis may be at risk for developing diabetes mellitus irrespective of antipsychotic use. This study aims to compare insulin resistance between antipsychotic-naïve first-episode psychosis patients and healthy controls. Methodology: Patients attending the psychiatry department of a tertiary care center were screened for antipsychotic-naïve first-episode psychosis. Diagnoses were made using the International Classification of Diseases-10 criteria. The psychosis severity was assessed using the Brief Psychiatric Rating Scale (BPRS). Healthy controls were recruited from hospital staff and patient attendants, matched for age, sex, and ethnicity. Fasting insulin and fasting glucose levels were measured, and insulin resistance was calculated using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) formula. Insulin resistance was compared between cases and controls, and its correlation with the severity of psychosis was assessed. Results: The median HOMA-IR scores were 1.1 for cases and 1.2 for controls, with no statistically significant difference between the groups. The correlation coefficient between BPRS scores and HOMA-IR was −0.315, which is not statistically significant. Conclusion: Insulin resistance did not differ significantly between individuals with first-episode psychosis and matched healthy controls.