Clinical Features of Bipolar Disorder with and without Comorbid Diabetes Mellitus

Abstract

Objective: Several papers have reported higher prevalence of diabetes mellitus (DM) type 2 in patients suffering from bipolar disorder (BD). The possible links between these 2 disorders include treatment, lifestyle, alterations in signal transduction, and possibly, a genetic link. To study this relation more closely, we investigated whether there are any differences in the clinical characteristics of BD patients with and without DM. Method: We compared the clinical data of 26 diabetic and 196 nondiabetic subjects from The Maritime Bipolar Registry. Subjects were aged 15 to 82 years, with psychiatric diagnoses of BD I ( n = 151), BD II ( n = 65), and BD not otherwise specified ( n = 6). The registry included basic demographic data and details on the clinical course of bipolar illness, its treatment, and physical comorbidity. In a subsequent analysis using logistic regression, we examined the variables showing differences between groups, with diabetes as an outcome variable. Results: The prevalence of DM in our sample was 11.7% ( n = 26). Diabetic patients were significantly older than nondiabetic patients ( P < 0.001), had higher rates of rapid cycling ( P = 0.02) and chronic course of BD ( P = 0.006), scored lower on the Global Assessment of Functioning Scale ( P = 0.01), were more often on disability for BD ( P < 0.001), and had higher body mass index ( P < 0.001) and increased frequency of hypertension ( P = 0.003). Lifetime history of treatment with antipsychotics was not significantly associated with an elevated risk of diabetes ( P = 0.16); however, the data showed a trend toward more frequent use of antipsychotic medication among diabetic subjects. Conclusions: Our findings suggest that the diagnosis of DM in BD patients is relevant for their prognosis and outcome.