Bipolar disorder and diabetes mellitus: epidemiology, etiology, and treatment implications

Bipolar disorder (BD) is a highly prevalent and disabling condition with significant mortality risk from suicide and other unnatural causes. This ignominious description is alongside recent observations that the majority of excess deaths in BD are secondary to medical comorbidity. The medical burden in BD is associated with a clustering of risk factors (e.g., obesity, smoking, unhealthy dietary habits) and inadequate utilization of preventative and primary healthcare. Diabetes mellitus (DM) is also a prevalent multifactorial disease which imparts substantial illness burden. Preliminary investigations indicate that patients who suffer from BD with comorbid DM have a more severe course and outcome, lower quality of life, higher prevalence of medical comorbidity and higher cost of illness. We conducted a MedLine search of all English-language articles 1966-2004 using the key words: bipolar disorder, major depressive disorder, diabetes mellitus, glucose metabolism, mortality, overweight, obesity, body mass index. The search was supplemented with manual review of relevant references. Priority was given to randomized controlled data, when unavailable; studies of sufficient sample size are presented. Subpopulations of BD patients should be considered at high risk for DM. The prevalence of DM in BD may be three times greater than in the general population. Bipolar disorder populations may be an at-risk group for glucose metabolic abnormalities. Opportunistic screening and vigilance for clinical presentations suggestive of DM is encouraged.