More research is needed to determine which factors may influence the increased incidence of diabetes -- nearly four times greater than the general population -- among people being treated for mental illness, says a University of Cincinnati report.Further investigation is necessary to clarify whether chronic mental illness itself is a risk factor for type 2 diabetes and obesity; whether some second-generation antipsychotic drugs affect metabolic risk factors associated with diabetes; whether mental illness has an impact on glucose regulation; and how co-morbid psychiatric conditions -- such as alcohol abuse, binge eating and nicotine dependence -- interact with psychotic and mood disorders to affect weight and diabetes risk.