Hyperglycemia and glycemic variability associated with glucocorticoids in women without pre-existing diabetes undergoing (neo) adjuvant taxane chemotherapy for early-stage breast cancer

Purpose: Glucocorticoids administered with chemotherapy cause hyperglycemia even in the non-diabetes setting. The prevalence of hyperglycemia and glycemic variability among breast cancer patients without diabetes are not well known, especially across different race/ethnicities. Methods: A retrospective cohort study was conducted involving early-stage breast cancer patients without diabetes who have received dexamethasone prior to (neo) taxane adjuvant chemotherapy between August 2017-December 2019. Random blood glucose levels were extracted, and steroid-induced hyperglycemia (SIH) was defined as a random glucose level of >140 mg/dL. Multivariate proportional hazards model was used to identify risk factors for SIH.Results: Of 100 total patients, the median age was 53 years (IQR: 45-63.5). Forty-five percent were non-Hispanic white, 28% Hispanic, 19% Asian, and 5% African American. The incidence of SIH was 67%, and glycemic fluctuations were highest in those with glucose levels >200 mg/dL. Non-Hispanic white remained as a significant predictor for time to SIH with a hazard ratio of 2.5 (95% CI: 1.04, 5.95, p=0.039). SIH was transient in over 90% patients, and only 7 patients remained hyperglycemic after glucocorticoid and chemotherapy completion.Conclusions: Pre-taxane dexamethasone-induced hyperglycemia in 67% of patients with the greatest glycemic lability in women with blood glucose level > 200 mg/dL. Non-Hispanic white had a higher risk of developing SIH. SIH patients should be monitored using a continuous glucose monitoring or self-monitoring of blood glucose devices. Diagnostic tests for diabetes such as HbA1c, oral glucose tolerance test, fasting plasma glucose, and endocrinology consultation should also be recommended.