Impaired glucose metabolism in bipolar patients and response to mood stabilizer treatments

Background: Metabolic dysfunctions in patients with bipolar disorder (BD) are critical factors that interfere with outcome, but only one study evaluated the influence of glucose dysmetabolism on the response to treatment with lithium. We aimed to investigate the potential impact of glucose metabolic status on clinical characteristics of BD patients and their response to treatment with different mood stabilizers in monotherapy or in combination. Methods: 45 BD patients with insulin resistance (IR) or type 2 diabetes mellitus (DM2) and 46 patients with normal glucose metabolism, treated with mood stabilizers for at least one year were assessed by diagnostic and rating instruments. Their clinical characteristics were compared and an ordinal logistic regression model was adopted to identify possible predictors of response to mood stabilizer treatments. Results: Compared to patients with normal glucose metabolism, BD patients with impaired glucose metabolism showed a worse clinical presentation of their psychiatric illness and a worse response to mood stabilizers. Ordinal logistic regression analysis evidenced that impaired glucose metabolism was the only predictor of poor response to mood stabilizers (OR 4.3; 95% CI: 1.7-11.1; p < 0.002). Limitations: Cross-sectional design and the relatively small sample size, are the main limitations of our study. Conclusions: Our findings expand literature data suggesting that BD patients with impaired glucose metabolism are at a greater risk of not responding to lithium as well as to different mood stabilizer treatments.