Abstract
BACKGROUND: Androgen-deprivation therapy (ADT) for prostate cancer (PCa) is associated with decreased insulin sensitivity and increased diabetes risk among nondiabetic men. Few data are available about the effects of ADT on diabetes control among men with diabetes. OBJECTIVE: We examined care for men who had diabetes at the time of PCa diagnosis to assess the effect of ADT on diabetes control, as measured by hemoglobin A1c (HbA1c) levels and the intensification of diabetes pharmacotherapy. DESIGN, SETTING, AND PARTICIPANTS: This was an observational cohort study using US Department of Veterans Affairs registry data and administrative data to assess HbA1c levels and intensification of diabetes pharmacotherapy among 2237 pairs of propensity-matched men with PCa and diabetes who were or were not treated with ADT. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We calculated the difference in difference of HbA1c levels at baseline and at 1 and 2 yr in the two groups, compared using a paired Student t test. We used a Cox proportional hazards model to estimate time to intensification of diabetes pharmacotherapy. RESULTS AND LIMITATIONS: The mean HbA1c at baseline was 7.24 (standard error [SE]: 0.05) for the ADT group and 7.24 (SE: 0.04) for the no-ADT group. HbA1c increased at 1 yr for men treated with ADT to 7.38 (SE: 0.04) and decreased among men not treated with ADT to 7.14 (SE: 0.04), for a difference in differences of +0.24 (p=0.008). Results were similar at 2 yr (p=0.03). The worsening HbA1c control occurred despite ADT being associated with an increased hazard of addition of diabetes medication (adjusted hazard ratio: 1.20; 95% confidence interval, 1.09-1.32). The limitation of this study was that it was observational and relied on administrative data. CONCLUSIONS: ADT is associated with worsening of diabetes control and increases in HbA1c levels despite the use of additional diabetes medications.