Impaired glucose homeostasis in first-episode schizophrenia: a systematic review and meta-analysis

Abstract

Context

Schizophrenia is associated with an increased risk of type 2 diabetes mellitus. However, it is not clear if schizophrenia confers an inherent risk for glucose dysregulation in the absence of the effects of chronic illness and long-term treatment.

Objective

To conduct a meta-analysis examining if individuals with first-episode schizophrenia already exhibit alterations in glucose homeostasis compared with controls.

Data sources

The Embase, Medline and PsycINFO databases were systematically searched for studies examining measures of glucose homeostasis in drug-naïve individuals with first episode schizophrenia compared with controls.

Study Selection

Of 3660 citations retrieved, 16 case control studies comprising 15 samples met inclusion criteria. The overall sample included 731 patients and 614 controls.

Data Extraction

Standardised mean differences in fasting plasma glucose, plasma glucose post-OGTT, fasting plasma insulin, insulin resistance, and HbA1c were calculated.

Data Synthesis

Fasting plasma glucose (g = 0.20 (95% CI 0.02 – 0.38, p = 0.027)), plasma glucose post-OGTT (g = 0.61 (95% CI 0.16 – 1.05, p = 0.007)), fasting plasma insulin (g = 0.41 (95% CI 0.09 – 0.72, p = 0.011)) and insulin resistance (HOMA-IR) (g = 0.34 (95% CI 0.14 – 0.54, p = 0.001)) were all significantly elevated in patients compared with controls. However, HbA1c levels (g = -0.08 (CI -0.34 – 0.18, p = 0.547) were not altered in patients compared with controls.

Conclusions

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.