Epidemiologic studies have found that elevated insulin levels and chronic hyperglycemia among breast cancer (BC) survivors are associated with poor prognosis; few of these studies have included Hispanic women in whom diabetes is highly prevalent. We examined the associations between circulating fructosamine-a biomarker of hyperglycemia and blood glucose control, self-reported diabetes, and risk of BC-specific and all-cause mortality among Hispanic and non-Hispanic white (NHW) women diagnosed with invasive BC. A total of 399 BC survivors (96 Hispanic, 303 NHW) contributed baseline data and plasma samples. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using multivariable Cox proportional hazards regression models. After a median follow-up time of 13 years, a total of 134 deaths occurred, of which 56 deaths were from BC. Diabetes was associated with BC-specific (HR, 2.89; 95% CI 1.27–6.60) and all-cause (HR, 2.10; 95% CI 1.24–3.55) mortality. Associations were stronger among women with clinically high fructosamine levels (>285 µmol/L) (BC-specific: HR, 4.25; 95% CI 1.67–10.80; all-cause: HR, 2.32; 95% CI 1.30–4.14) compared to women with normal levels (≤285 µmol/L). In mediation analysis, fructosamine explained 47% of the association between diabetes and all-cause mortality and 41% of BC-specific mortality; the largest attenuation was among Hispanics for all-cause mortality (56%). Our results demonstrate that poor glycemic control explains a large extent of the relationship between diabetes and mortality among women with invasive BC, particularly among Hispanic women. The associations we observed for BC mortality should be confirmed in larger studies of ethnically diverse BC patients.

流行病学研究发现，乳腺癌（BC）幸存者中胰岛素水平升高和慢性高血糖与预后不良有关。这些研究很少包括糖尿病患病率很高的西班牙裔女性。我们研究了被诊断患有侵袭性 BC 的西班牙裔和非西班牙裔白人 (NHW) 女性中循环果糖胺（高血糖和血糖控制的生物标志物）、自我报告的糖尿病以及 BC 特异性和全因死亡率风险之间的关联。共有 399 名 BC 幸存者（96 名西班牙裔，303 名 NHW）贡献了基线数据和血浆样本。使用多变量 Cox 比例风险回归模型计算风险比 (HR) 和 95% 置信区间 (CI)。中位随访时间为 13 年后，总共发生 134 例死亡，其中 56 例死亡来自 BC。糖尿病与 BC 特异性死亡率（HR，2.89；95% CI 1.27-6.60）和全因死亡率（HR，2.10；95% CI 1.24-3.55）相关。与临床上果糖胺水平较高 (>285 µmol/L) 的女性相比，相关性更强（BC 特异性：HR，4.25；95% CI 1.67–10.80；全因：HR，2.32；95% CI 1.30–4.14）正常水平（≤285 µmol/L）的女性。在中介分析中，果糖胺解释了 47% 的糖尿病与全因死亡率之间的关联以及 41% 的 BC 特异性死亡率；西班牙裔的全因死亡率下降幅度最大（56%）。我们的研究结果表明，血糖控制不佳在很大程度上解释了患有侵袭性乳腺癌的女性（尤其是西班牙裔女性）糖尿病与死亡率之间的关系。我们观察到的 BC 死亡率相关性应该在针对不同种族 BC 患者的更大规模研究中得到证实。