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. 2023 Jan 30;38(4):e24.
doi: 10.3346/jkms.2023.38.e24.

Long-Term Risk of Cardiovascular Disease Among Type 2 Diabetes Patients According to Average and Visit-to-Visit Variations of HbA1c Levels During the First 3 Years of Diabetes Diagnosis

Hyunah Kim  1 , Da Young Jung  2 , Seung-Hwan Lee  3 , Jae-Hyoung Cho  3 , Hyeon Woo Yim  4 , Hun-Sung Kim  3   5
Affiliations

Long-Term Risk of Cardiovascular Disease Among Type 2 Diabetes Patients According to Average and Visit-to-Visit Variations of HbA1c Levels During the First 3 Years of Diabetes Diagnosis

Hyunah Kim et al. J Korean Med Sci. .

Abstract

Background: It remains unclear whether a combination of glycemic variability and glycated hemoglobin (HbA1c) status leads to a higher incidence of cardiovascular disease (CVD). Therefore, to investigate CVD risk according to the glucose control status during early diabetes, we examined visit-to-visit HbA1c variability among patients with type 2 diabetes (T2DM).

Methods: In this 9-year retrospective study, we measured HbA1c levels at each visit and tracked the change in HbA1c levels for 3 years after the first presentation (observation window) in newly diagnosed T2DM patients. We later assessed the occurrence of CVD in the last 3 years (target outcome window) of the study period after allowing a 3-year buffering window. The HbA1c variability score (HVS; divided into quartiles, HVS_Q1-4) was used to determine visit-to-visit HbA1c variability.

Results: Among 4,817 enrolled T2DM patients, the mean HbA1c level was < 7% for the first 3 years. The group with the lowest HVS had the lowest rate of CVD (9.4%; 104/1,109 patients). The highest incidence of CVD of 26.7% (8/30 patients) was found in HVS [≥ 9.0%]_Q3, which was significantly higher than that in HVS [6.0-6.9%]_Q1 (P = 0.006), HVS [6.0-6.9%]_Q2 (P = 0.013), HVS [6.0-6.9%]_Q3 (P = 0.018), and HVS [7.0-7.9%]_Q3 (P = 0.040).

Conclusion: To our knowledge, this is the first long-term study to analyze the importance of both HbA1c change and visit-to-visit HbA1c variability during outpatient visits within the first 3 years. Lowering glucose levels during early diabetes may be more critical than reducing visit-to-visit HbA1c variability.

Keywords: Blood Glucose; Cardiovascular Disease; Diabetes Mellitus; Glycated Hemoglobin (HbA1c); HbA1c Variability Score.

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Conflict of interest statement

The authors have no potential conflicts of interest to disclose.

Figures

Fig. 1
Fig. 1. The 9-year research design showing the observation, buffering and outcome windows (3 years each). The observation window indicates the first detection of type 2 diabetes, and the target outcome window indicates the detection of CVD after the 3-year buffering window.
CVD = cardiovascular disease, HbA1c = glycated hemoglobin.
Fig. 2
Fig. 2. Flowchart of patient selection for the study.
HVS = glycated hemoglobin variability score.
Fig. 3
Fig. 3. Comparison of the incidence of CVD according to baseline HbA1c and the HVS P values were calculated using the χ2 test or aFisher’s exact test for categorical variables.
HbA1c = glycated hemoglobin, HVS = glycated hemoglobin variability score, NS = not significant, CVD = cardiovascular disease.
Fig. 4
Fig. 4. Cumulative incidence of CVD (n = 4,817).
HVS = glycated hemoglobin variability score, CVD = cardiovascular disease.
See this image and copyright information in PMC

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