The longitudinal course of bipolar disorder is heterogeneous, and is moderated by the presence of general medical comorbidities. The authors of this study investigated the moderating effects of impaired glucose metabolism on variables of illness course and severity in a bipolar population.
Fifty-five patients with bipolar disorder were evaluated. All subjects were evaluated with respect to current and past psychiatric and medical disorders, as well as lifetime use of any medication. Body mass index (BMI) and metabolic parameters were obtained. Impaired glucose metabolism was operationalized as pre-diabetes or type 2 diabetes mellitus.
Thirty (54.5%) individuals had impaired glucose metabolism. After adjustment for age, gender, ethnicity, alcohol use, smoking, BMI and past and current exposure to psychotropic medications, individuals with impaired glucose metabolism, when compared to euglycemic participants, had an earlier age of onset, longer illness duration, a higher number of previous manic/hypomanic episodes and a higher ratio of manic/hypomanic to depressive episodes. Moreover, they observed a moderating effect of impaired glucose metabolism on the association between number of mood episodes and other variables of illness course, with the correlation between lifetime mood episodes and frequency of episodes being significantly greater in the impaired glucose metabolism subgroup. All associations remained significant after adjusting for relevant confounding factors (e.g. age, alcohol and tobacco use, exposure to psychotropic agents, BMI).
While the sample size was small, the authors suggest that comorbid impaired glucose metabolism may be a key moderator of illness progression in bipolar disorder.
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Mansur RB, Rizzo LB, Santos CM, Asevedo E, Cunha GR, Noto MN, Pedrini M, Zeni M, Cordeiro Q, McIntyre RS and Brietzke E: Impaired glucose metabolism moderates the course of illness in bipolar disorder. J. Affect. Disord. 195: 57-62 (2016).
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http://www.ncbi.nlm.nih.gov/pubmed/26866976