Elevated frequency of diabetes mellitus in hospitalized manic-depressive patients

Objective: Disturbance in glucose homeostasis in psychiatric populations ha s been suggested since the early part of this century. Increased comorbidit y of diabetes mellitus in persons with major mood disorders has also been s uggested. The goal of this study was to determine whether subjects diagnose d with bipolar disorder have an elevated rate of comorbid diabetes mellitus . Method: Three hundred forty-five hospitalized patients, aged 20-74 years, who mel the DSM-III-R criteria for bipolar disorder, manic or mixed subtyp e, were evaluated for a comorbid diagnosis of diabetes mellitus. The freque ncy of diabetes mellitus in the study group was determined and compared wit h the expected frequency, calculated as a weighted average based on sex and age from national norms. Variables characterizing the course and severity of the affective disorder in the group of diabetic bipolar subjects and a g roup of nondiabetic age-matched bipolar subjects were compared. Results: Th e prevalence of diabetes mellitus among these bipolar patients was 9.9% sig nificantly greater than expected from national norms (3.4%). The patients w ith comorbid diabetes mellitus had significantly more lifetime psychiatric hospitalizations than the nondiabetic subjects, but age at first hospitaliz ation and duration of psychiatric disorder were similar in the two groups. Conclusions: The frequency of diabetes mellitus in hospitalized patients di agnosed with bipolar disorder is higher than in the general population. Man ic-depressive patients with diabetes mellitus have a more severe course of illness, as indicated by a greater number of psychiatric hospitalizations. Possible reasons for this increased comorbidity include a genetic relations hip between the disorders, a causal relationship in which hypercortisolemia induces diabetes or diabetic vascular lesions contribute to mania, an over lapping functional disturbance affecting similar regions of the brain, or t he effect of psychotropic medications.