Chehregosha Haleh, Khamseh Mohammad E, Malek Mojtaba, Hosseinpanah Farhad, Ismail-Beigi Faramarz
Endocrine Research Center (Firouzgar), Institute of Endocrinology and Metabolism, Iran University of Medical Sciences (IUMS), Tehran, Iran.
Research Center for Prevention of Cardiovascular Disease, Institute of Endocrinology and Metabolism, Iran University of Medical Sciences (IUMS), Tehran, Iran.
Diabetes Ther. 2019 Jun;10(3):853-863. doi: 10.1007/s13300-019-0619-1. Epub 2019 Apr 29.
Hemoglobin A1C (HbA1c) is used as an index of average blood glucose measurement over a period of months and is a mainstay of blood glucose monitoring. This metric is easy to measure and relatively inexpensive to obtain, and it predicts diabetes-related microvascular complications. However, HbA1c provides only an approximate measure of glucose control; it does not address short-term glycemic variability (GV) or hypoglycemic events. Continuous glucose monitoring (CGM) is a tool which helps clinicians and people with diabetes to overcome the limitations of HbA1c in diabetes management. Time spent in the glycemic target range and time spent in hypoglycemia are the main CGM metrics that provide a more personalized approach to diabetes management. Moreover, the glucose management indicator (GMI), which calculates an approximate HbA1c level based on the average CGM-driven glucose level, facilitates individual decision-making when the laboratory-measured HbA1c and estimated HbA1c are discordant. GV, on the other hand, is a measure of swings in blood glucose levels over hours or days and may contribute to diabetes-related complications. In addition, addressing GV is a major challenge during the optimization of glycemia. The degree of GV is associated with the frequency, duration, and severity of the hypoglycemic events. Many factors affect GV in a patient, including lifestyle, diet, the presence of comorbidities, and diabetes therapy. Recent evidence supports the use of some glucose-lowering agents to improve GV, such as the new ultra-long acting insulin analogs, as these agents have a smoother pharmacodynamic profile and improve glycemic control with fewer fluctuations and fewer nocturnal hypoglycemic events. These newer glucose-lowering agents (such as incretin hormones or sodium-glucose cotransporter 2 inhibitors) can also reduce the degree of GV. However, randomized trials are needed to evaluate the effect of GV on important diabetes outcomes. In this review, we discuss the role of HbA1c as a measure of glycemic control and its limitations. We also explore additional glycemic metrics, with a focus on time (duration) in glucose target range, time (duration) in hypoglycemia, GV, GMI, and their correlation with clinical outcomes.
糖化血红蛋白（HbA1c）用作数月期间平均血糖测量的指标，是血糖监测的主要手段。该指标易于测量且获取成本相对较低，并且能够预测糖尿病相关的微血管并发症。然而，HbA1c仅提供血糖控制的大致测量；它无法解决短期血糖变异性（GV）或低血糖事件。连续血糖监测（CGM）是一种有助于临床医生和糖尿病患者克服HbA1c在糖尿病管理中局限性的工具。处于血糖目标范围内的时间和处于低血糖状态的时间是主要的CGM指标，它们为糖尿病管理提供了更个性化的方法。此外，葡萄糖管理指标（GMI）根据平均CGM驱动的血糖水平计算出近似的HbA1c水平，当实验室测量的HbA1c与估算的HbA1c不一致时，有助于个人决策。另一方面，GV是衡量数小时或数天内血糖水平波动的指标，可能会导致糖尿病相关并发症。此外，在优化血糖期间解决GV是一项重大挑战。GV的程度与低血糖事件的频率、持续时间和严重程度相关。许多因素会影响患者的GV，包括生活方式、饮食、合并症的存在以及糖尿病治疗。最近的证据支持使用一些降糖药物来改善GV，例如新型超长效胰岛素类似物，因为这些药物具有更平稳的药效学特征，并且能以更少的波动和更少的夜间低血糖事件改善血糖控制。这些新型降糖药物（如肠促胰岛素激素或钠-葡萄糖协同转运蛋白2抑制剂）也可以降低GV的程度。然而，需要进行随机试验来评估GV对重要糖尿病结局的影响。在本综述中，我们讨论了HbA1c作为血糖控制指标的作用及其局限性。我们还探讨了其他血糖指标，重点关注处于葡萄糖目标范围内的时间（持续时间）、处于低血糖状态下的时间（持续时间）、GV、GMI以及它们与临床结局的相关性。
