Psychiatric co-morbidity with type 1 and type 2 diabetes mellitus.

We evaluated the prevalence of diabetes comorbidity in Greek psychiatric patients, differences between type 1 and type 2 diabetics and the outcome of psychiatric disorder. Of 800 psychiatric patients meeting our inclusion criteria, 82 (10.2%) had diabetes mellitus; 28% type 1 and 72% type 2. The mean age at onset of mental illness was earlierfortype 1 diabetics (mean 26.95, SD 9.09 years) than type 2 (mean 33.22, SD 10.71 years) (P < 0.015) and the duration of untreated mental illness was shorter (mean 2.86, SD 3.06 years compared with mean 4.13, SD 6.24 years for type 2 diabetics). Schizophrenia was the commonest psychiatric diagnosis in both types of diabetes. There was no significant difference in outcome of psychiatric disorder between the 2 types of diabetics. Existence of diabetes mellitus (regardless of type), duration of untreated mental illness and lack of patient therapeutic education were negative predictors of (unfavourable) outcome. These findings provide evidence of a high prevalence of diabetes in psychiatric patients and that having diabetes has an adverse effect on outcome of psychiatric illness.