Abstract
Background: Schizophrenia is associated with an increased risk of type 2 diabetes mellitus. However, it is not clear whether schizophrenia confers an inherent risk for glucose dysregulation in the absence of the effects of chronic illness and long-term treatment. Our objective was to conduct a meta-analysis examining whether individuals with first-episode schizophrenia already exhibit alterations in glucose homeostasis compared with controls.
Methods: The Embase, Medline and PsycINFO databases were systematically searched for studies examining measures of glucose homeostasis in drug-naive individuals with first-episode schizophrenia compared to controls. Of 3660 citations retrieved, 16 case–control studies comprising 15 samples met inclusion criteria. The overall sample included 731 patients and 614 controls. Standardized mean differences in fasting plasma glucose, plasma glucose post-OGTT, fasting plasma insulin, insulin resistance, and HbA1c were calculated.
Results: Fasting plasma glucose (g = 0.199 (95% CI 0.022–0.376, P = .028)), plasma glucose post-OGTT (g = 0.605 (95% CI 0.163–1.047, P = .007)), fasting plasma insulin (g = 0.409 (95% CI 0.093–0.724, P = .011)) and insulin resistance (HOMA-IR; g = 0.334 (95% CI 0.135–0.534, P = .001)) were all significantly elevated in patients compared with controls. However, HbA1c levels (g = −0.08 (CI −0.340 to 0.180, P = .547) were not altered in patients compared with controls.
Conclusion: These findings show glucose homeostasis is altered from illness onset in schizophrenia, indicating patients are at increased risk of diabetes mellitus as a result. This has implications for the monitoring and treatment choice for patients with schizophrenia.