Meta-analysis of glucose tolerance, insulin, and insulin resistance in antipsychotic-naïve patients with nonaffective psychosis

Abstract Background Some studies have suggested that antipsychotic-naive patients with nonaffective psychosis (NAP) have glucose intolerance. Aims To conduct a systematic review and meta-analysis of fasting glucose (FG), two hour values in the oral glucose tolerance test (2HG), fasting insulin concentration (INS), and insulin resistance (IR). Method We identified possibly relevant studies, then selected studies, following usual guidelines, with two authors reviewing the manuscripts. We required studies to include subjects with nonaffective psychosis and control subjects. Results There were 911 patients and 870 control subjects in the analysis of FG; their average ages were respectively 28.7 and 29.5 years. Significant differences were found for all four variables, with effect size estimates ranging from 0.21 to 0.58. Conclusions As a group, at the time of first clinical contact for psychosis, people with NAP have a slight increase in FG, which most of them maintain in the normal range despite a small increase in IR by secreting additional INS. When faced with a physiological challenge such as a glucose tolerance test or antipsychotics, they are no longer able to maintain a normal glucose concentration.