OBJECTIVE Hemoglobin A_1c (HbA_1c) can be used to assess type 2 diabetes (T2D) risk. We asked whether HbA_1c was associated with T2D risk in four scenarios of clinical information availability: 1) HbA_1c alone, 2) fasting laboratory tests, 3) clinic data, and 4) fasting laboratory tests and clinic data.

RESEARCH DESIGN AND METHODS We studied a prospective cohort of white (N = 11,244) and black (N = 2,294) middle-aged participants without diabetes in the Framingham Heart Study and Atherosclerosis Risk in Communities study. Association of HbA_1c with incident T2D (defined by medication use or fasting glucose [FG] ≥126 mg/dL) was evaluated in regression models adjusted for 1) age and sex (demographics); 2) demographics, FG, HDL, and triglycerides; 3) demographics, BMI, blood pressure, and T2D family history; or 4) all preceding covariates. We combined results from cohort and race analyses by random-effects meta-analyses. Subsidiary analyses tested the association of HbA_1c with developing T2D within 8 years or only after 8 years.

RESULTS Over 20 years, 3,315 individuals developed T2D. With adjustment for demographics, the odds of T2D increased fourfold for each percentage-unit increase in HbA_1c. The odds ratio (OR) was 4.00 (95% CI 3.14, 5.10) for blacks and 4.73 (3.10, 7.21) for whites, resulting in a combined OR of 4.50 (3.35, 6.03). After adjustment for fasting laboratory tests and clinic data, the combined OR was 2.68 (2.15, 3.34) over 20 years, 5.79 (2.51, 13.36) within 8 years, and 2.23 (1.94, 2.57) after 8 years.

CONCLUSIONS HbA_1c predicts T2D in different common scenarios and is useful for identifying individuals with elevated T2D risk in both the short- and long-term.

目的血红蛋白A _1c（HbA _1c）可用于评估2型糖尿病（T2D）的风险。我们询问HbA _1c是否在以下四种临床信息可用性情景中与T2D风险相关：1）单独的HbA _1c，2）禁食实验室检查，3）临床数据以及4）禁食实验室检查和临床数据。

研究设计和方法我们在弗雷明汉心脏研究和社区动脉粥样硬化风险研究中研究了白人（N = 11,244）和黑人（N = 2,294）没有糖尿病的中年受试者的预期队列。糖化血红蛋白的关联_1C用入射T2D（由药物使用或空腹血糖[FG]≥126毫克/分升的定义）在调整回归模型进行评价1）年龄和性别（人口统计）; 2）人口统计资料，FG，HDL和甘油三酸酯；3）人口统计学，BMI，血压和T2D家族史；或4）所有前面的协变量。我们通过随机效应荟萃分析将队列分析和种族分析的结果相结合。辅助分析测试了HbA _1c在8年内或仅在8年后与发展中的T2D的关联。

结果在20年的时间里，有3,315个人开发了T2D。随着人口统计的调整，HbA _1c的每增加一个百分比，T2D的几率就会增加四倍。黑人的比值比（OR）为4.00（95％CI 3.14，5.10），而白人为4.73（3.10，7.21），因此OR值为4.50（3.35，6.03）。调整禁食实验室检查和临床数据后，在20年内的总OR为2.68（2.15，3.34），在8年内为5.79（2.51，13.36），在8年后为2.23（1.94，2.57）。

结论HbA _1c可在不同的常见情况下预测T2D，可用于识别短期和长期T2D风险升高的个体。