Parental type 2 diabetes in patients with non-affective psychosis.

OBJECTIVE: People with schizophrenia have an increased risk of diabetes that may be independent of antipsychotics. Previous studies have explored the prevalence of a family history of type 2 diabetes (DM2) in schizophrenia. We hypothesized that parental DM2 is increased in probands with non-affective psychosis (NAP) compared to controls, and parental DM2 predicts comorbid diabetes in NAP, after controlling for potential confounders.

METHOD: N=217 patients with NAP and N=67 controls were interviewed for a history of parental DM2. NAP was investigated as a predictor of parental DM2 in binary logistic regression models, controlling for age, sex, race, smoking, body mass index, socioeconomic status, and parental psychiatric history.

RESULTS: There was an increased prevalence of DM2 in the mother (30.0% vs 13.8%, p=0.013) and in either the mother or father (44.5% vs 24.6%, p=0.006) in patients with NAP versus controls. After accounting for potential confounders, NAP was associated with significant increased odds of parental DM2 (OR=2.80, 95% CI 1.08-7.23, p=0.034). Parental DM2 was also associated with increased odds of comorbid DM2 in NAP (OR=3.67, 95% CI 1.58-8.56, p=0.003).

CONCLUSIONS: We replicated an association of an increased prevalence of parental DM2 in patients with NAP. Parental DM2 was also an independent predictor of comorbid DM2 in these patients. These associations may be due to shared environmental or genetic risk factors, or gene by environment interactions. Given risks of incident diabetes with antipsychotic treatment, screening for parental DM2 status is germane to the clinical care of patients with NAP.