Effects of psychotropics on glycosylated hemoglobin (HbA1c) in a cohort of bipolar patients

OBJECTIVES: Research suggests that certain psychotropics may induce glucose regulatory dysfunction. Hyperglycemia increases levels of glycosylated hemoglobin (HbA1c). This study investigated the relationship between psychotropic use and concentrations of HbA1c in bipolar patients who were presumably non-diabetic. METHODS: Analysis was conducted on 76,671 patients with bipolar disorder (BPD) from the Integrated Health Care Information Services (IHCIS). Included were 381 patients with at least two measurements of HbA1c taken between January 1, 1997 and June 30, 2002. Individuals with only 1 HbA1c measure, diagnosed with type 1 or type 2 diabetes according to the International Classification of Diseases (ICD-9), and/or who were using any anti-diabetes medication were excluded from the cohort. We compared HbA1c levels from first to final HbA1c measurements. The types of psychotropic medications used by the patients were examined. RESULTS: A total of 197 (51.9%) BPD patients had an abnormal initial HbA1c test result (defined as HbA1c>7). Thirty patients were taking antipsychotics, 24 mood stabilizers (anticonvulsants), 10 lithium, 51 antidepressants and 116 a combination of medications. A total of 150 patients were not taking psychotropic medications. HbA1c levels declined significantly in patients taking psychotropic medication(s) [mean=7.5, standard deviation (SD)=2.1% versus mean=7.0, SD=1.8%; p<0.001] and in patients not taking psychotropic medication(s) (mean=7.4, SD=2.0% versus mean=7.0, SD=1.9%; p<0.001). The only exception to this finding was among patients taking antipsychotics, where there was a slight increase (not statistically significant) during this period (mean=7.0, SD=1.8% versus mean=7.2, SD=3.7%; p=0.791). CONCLUSIONS: These results support findings suggesting an increased risk of type 2 diabetes in BPD patients. Mood stabilizers (anticonvulsants), antidepressants and lithium in monotherapy and combination were associated with a decrease in HbA1c levels. Although not statistically significant, antipsychotic medications were associated with an increase in HbA1c in this population.