The CDS Diabetes Guidelines are heavily updated. Why are cutting-edge blood glucose control indicators so popular?

How to practice clinically? In April 2021, the Diabetes Branch (CDS) of the Chinese Medical Association issued the "Guidelines for the Prevention and Treatment of Type 2 Diabetes in China (2020 Edition)"1.

Based on national conditions, this guide combines the latest evidence-based evidence at home and abroad to provide scientific, authoritative, advanced and practical reference for the diagnosis and treatment of diabetes.

 Among them, in the blood glucose monitoring part of the guideline, the glucose target range time (Time in range, TIR) was included in the blood glucose control goal 1 for the first time, defining higher-quality blood glucose management content.

As a cutting-edge indicator of blood glucose control, why is TIR recommended by the guidelines, and how can TIR be used clinically to better assist blood glucose management? Blood glucose fluctuation: the indispensable "fourth dimension" for sugar control.
Blood glucose fluctuation refers to the unstable state in which the blood glucose level changes between its peak and trough2.

Compared with persistent hyperglycemia, blood glucose fluctuations are even more harmful to chronic complications of diabetes2.

Blood glucose fluctuations activate oxidative stress pathways, damage endothelial cell function, exacerbate chronic inflammation, and cause vascular damage, increasing the risk of diabetes complications, including macrovascular complications and microvascular complications2.

 Glycated hemoglobin (HbA1c) has always been regarded as the "gold standard" that reflects the status of blood sugar control, but it cannot reflect blood sugar fluctuations and has clinical limitations.

Therefore, in addition to HbA1c, postprandial blood glucose (PPG) and fasting blood glucose (FPG), blood glucose fluctuation is the fourth dimension of blood glucose control that is equally important for blood glucose control.

TIR can be used as a new indicator to evaluate short-term blood glucose fluctuations, reflecting the patient's blood glucose fluctuation status throughout the day.

 TIR refers to the time (expressed in min) or the percentage of glucose within the target range (usually 3.
9 to 10.
0 mmol/L) within 24 h1.In addition, TIR is linearly related to HbA1c, and HbA1c3 can also be estimated to a certain extent.

 A number of studies have shown that TIR is significantly associated with diabetic retinopathy, major adverse cardiovascular events (MACE), all-cause and cardiovascular disease death risks4,5,6, and increasing TIR levels can help reduce microvessels and macrovessels in diabetic patients Risk of complications7,8.

The above results suggest that TIR is expected to become an effective indicator for evaluating blood sugar control.

As early as 2017, the international consensus issued by the International Conference on Advanced Technology and Treatment of Diabetes (ATTD) included TIR as a CGM monitoring indicator for the first time9.
Subsequently, the 2020 American Diabetes Association (ADA) guidelines formally recommended TIR to assess blood glucose management status10.
The CDS guidelines also recommend that TIR be included in blood glucose control goals1.

 Three ways to obtain TIR in this way.
So, by which ways can TIR be obtained? The following three blood glucose monitoring methods can be used to calculate TIR, namely continuous blood glucose monitoring (CGM), instantaneous scanning glucose monitoring system (FGM) and self blood glucose monitoring (SMBG).

 TIR can be read directly by wearing CGM or FGM.

The 2021 American Diabetes Association (ADA) guidelines point out that CGM is recommended for patient TIR management.
All CGM devices should be able to output standardized, single-page, blood glucose reports with visual details, such as visual blood glucose analysis reports (AGP) 11.

AGP is a CGM standardized report that is unanimously recognized and recommended by the global guidelines, and five smooth curves represent the key parameters of the blood glucose monitoring system (Figure 1) 12,13.

The "three-step method" is generally recommended to read the picture: first look at the time to reach the target, second look at blood sugar fluctuations, third look at the risk of hypoglycemia12.

Figure 1: An example of an AGP report.
For example, using SMBG data to calculate TIR, it is generally required to test blood glucose at 7 points (before and after meals + before going to bed), and then calculate the proportion of TIR (3.
9-10.
0mmol/L) at 7 points.
The number of digits is 14, 15.  TIR in clinical practice: varies from person to person.
The consensus issued by ATTD in 2019 recommends that the blood glucose target range for patients with type 1 diabetes (T1DM) and type 2 diabetes (T2DM) be set at 3.
9-10.
0 mmol/L, and patients with T1DM and T2DM The TIR control target is >70%13.

Every 5% increase in TIR will bring significant clinical benefits to patients with T1DM and T2DM13.

The 2020 CDS guidelines recommend that TIR should be highly individualized, while paying attention to patients' hypoglycemia and blood glucose fluctuations1.

 For elderly or high-risk T2DM populations, it is recommended to reduce the TIR target from >70% to >50%, and reduce the time of glucose below the target range (TBR) to <1% to place more emphasis on reducing hypoglycemia.
It is not an emphasis on maintaining a target blood glucose13; during pregnancy, the goal of blood glucose control is to safely increase TIR as quickly as possible, while reducing the time the glucose is above the target range (TAR) and blood glucose variability13.

In addition, based on the risk of diabetic complications, a stratified TIR individualized target can be set 16 (Figure 2).

 Figure 2: Based on the risk of diabetic complications, stratified TIR individualized goals have been established.
In terms of treatment, life>
A study enrolled 24 patients with T2DM who were treated with insulin dexamethasone once a day for 8 weeks.
FGM was used to observe the blood sugar control status.
The results showed that dexamethasone treatment was effective in controlling glucose and TIR as high as 77.
3%13; real-world studies have also confirmed that others The basal insulin is converted to glutathione treatment, blood sugar control is more stable, and TIR can be increased by 13%18 (Figure 3).

Figure 3: The conversion of other basal insulins to glutathione treatment results in smoother blood glucose control.
In addition to FPG, PPG and HbA1c, blood glucose fluctuations are an important part of the goal of blood glucose control in diabetic patients.

The 2020 CDS guidelines included TIR, which reflects blood glucose fluctuations, into the blood glucose control target for the first time.

Clinically, TIR can be obtained through CGM, FGM and SMBG.

The control goal of TIR should be highly individualized, while paying attention to patients' hypoglycemia and blood sugar fluctuations.

Life>
It is worth noting that TIR reflects short-term blood glucose fluctuations, which need to be combined with other glucose control indicators for comprehensive assessment, and we look forward to more Chinese evidence to improve TIR.

Expert introduction: Professor Shi Lixin, Director of the Department of Endocrinology, Affiliated Hospital of Guizhou Medical University, Member of the Standing Committee of the Chinese Medical Association Diabetes Branch and Secretary General, Chairman of the Diabetes Neurological Complications Group of the Chinese Medical Association, Chairman of the Diabetes Neurocomplications Group, Chinese Medical Doctor Association Endocrinology Member of the Standing Committee of the Branch of Metabolic Physicians, Chairman of the Endocrinology and Diabetes Branch of the Guizhou Medical Association, Deputy Editor of Endocrine Reviews Chinese Edition, "Chinese Journal of Internal Medicine", "Chinese Journal of Endocrinology and Metabolism", "Chinese Journal of Diabetes" Editorial Board of DMRR Magazine Reference Materials :1.
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