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

BACKGROUND: Some studies have suggested that antipsychotic-naïve 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 29.5years. 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.