A Meta-Analysis of Abnormal Glucose Metabolism in First-Episode Drug-Naive Schizophrenia.

Background: Patients with schizophrenia exhibit a higher mortality rate compared with the general population. This mortality has been attributed predominantly by the high risk of type 2 diabetes mellitus in the patients. We aimed to assess the inherent risk of glucose metabolism abnormalities in first-episode drug-naive schizophrenia.
Subjects and Methods: We searched English database (PubMed, EMBASE, MEDLINE, Cochrane Library databases) and Chinese database (Wan Fang Data, CBM disc, VIP, and CNKI) from their inception until Jul 2018 for case-control studies examining glucose metabolism abnormalities. Measurements, such as fasting plasma glucose levels, fasting plasma insulin levels, insulin resistance and HbA1c levels in first-episode antipsychotic-naive patients were used to test for prediabetes. Standardized/weighted mean differences and 95% confidence intervals were calculated and analyzed.
Results: 19 studies (13 in English and 6 in Chinese) consisting of 1065 patients and 873 controls were included. Fasting plasma glucose levels (95% CI; 0.02 to 0.29; P=0.03), 2 h plasma glucose levels after an OGTT (95% CI; 0.63 to 1.2; P<0.00001), fasting plasma insulin levels (95% CI; 0.33 to 0.73; P<0.00001), insulin resistance (95% CI; 0.29 to 0.6; P<0.00001) in patients with first-episode schizophrenia were significant elevated. There was no significant difference in HbA1c level (95% CI; -0.34 to 0.18; P=0.54) in patients with first-episode schizophrenia compared with controls.
Conclusions: This meta-analysis showed that glucose metabolism was impaired in patients with first-episode schizophrenia. Higher quality studies with larger samples are warranted to confirm these findings.