Mood-stabilizing medications are less likely to be effective for patients with bipolar disorder who also have diabetes or are insulin resistant, according to a new study.
Martin Alda, MD, of Dalhousie University in Halifax, Canada, and colleagues found that bipolar disorder patients who had insulin resistance or Type 2 diabetes were three times more likely to suffer from rapid cycling.
The study consisted of 121 patients with bipolar disorder. About one-third had insulin resistance and 21.5% of had Type 2 diabetes.
Half of patients with Type 2 diabetes and 48.7% of those with insulin resistance had rapid cycling compared to 27.3% of patients with normal blood sugar levels, the reserchers reported in The British Journal of Psychiatry.
The researchers also found that patients with impaired glucose metabolism were also more likely to be resistant to lithium treatment. Just 3.2% of those with normal glucose metabolism were resistant to lithium, but 36.7% and 36.8% of patients with insulin resistance and diabetes, respectively, failed to respond to lithium.
The study results indicate the importance of diagnosing and treating insulin resistance in patients with bipolar disorder. However, researchers noted that they could not prove that insulin resistance actually causes bipolar treatment resistance.
Patients with bipolar disorder who are insulin resistant are likely to also be refractory to mood-stabilizing treatment, according to researchers.
Martin Alda, MD of Dalhousie University, Halifax, Canada, and team note that their cross-sectional study could not prove that insulin resistance actually causes bipolar treatment resistance.
“Experimental studies will be required to determine whether normalization of glucose metabolism will affect course and treatment outcomes among patients with bipolar disorder”, they write in The British Journal of Psychiatry.