Aims: To determine whether there is an association between Type 2 diabetes mellitus and schizophrenia, independent of medication.
Methods: In this cross-sectional study we performed an oral glucose tolerance test on 38 non-obese white Caucasians who fulfilled the criteria for first-episode drug-naïve schizophrenia, 38 control subjects (matched for age, gender, smoking status, alcohol intake and ethnicity) and 44 first-degree relatives of the patients.
Results: The frequency of impaired glucose tolerance (IGT), defined by World Health Organization criteria, was 10.5% (n = 4) in patients with schizophrenia, 18.2% (n = 8) in unaffected relatives and 0.0% in healthy control subjects (chi(2) = 4.22, d.f. = 2, P < 0.05).
Conclusions: The high point prevalence of IGT in never-treated patients and relatives supports either shared environmental or genetic predisposition to IGT. Both patients and their relatives present an ideal cost-effective opportunity to screen for Type 2 diabetes mellitus, as they are both easily identifiable.