China: Abnormal ankle-brachial index (ABI) in patients with type 2 diabetes is associated with lower time in range (TIR), and the correlation is more robust than HbA1C, a recent study in Cardiovascular Diabetology has claimed. Therefore, TIR's role should be stressed in evaluating lower limb vascular diseases.

Time in range is a novel proxy measure of glucose control. It is closely related to diabetic microangiopathy and other chronic complications, but no studies have examined the correlation between TIR and lower limb angiopathy. Therefore, Yinghua Wei from the Medical School of Nanjing University in Jiangsu, China, and colleagues aimed to investigate the relationship between TIR and abnormal ankle-brachial index in type 2 diabetes.

For this purpose, the researchers retrospectively collected patients' information from the database and conducted a cross-sectional analysis. They enrolled a total of 405 patients with type 2 diabetes. ABI was measured and graded into low, normal, and high groups on the basis of the ABL values of ≤ 0.9, > 0.9 and < 1.3, ≥ 1.3. All patients underwent CGM (continuous glucose monitoring). TIR was defined as the time percentage in which blood sugar was in the range of 3.9–10 mmol/L during a period of 24-h. Spearman analysis was used to examine correlations between TIR and abnormal ABI. The authors used logistic regression to explore whether TIR is an independent risk factor for abnormal ABI.
The study led to the following findings:
· The overall prevalence of abnormal ankle-brachial index was 20.2% (low 4.9% and high 15.3%).
· In patients with abnormal ABI values, TIR was lower.
· With increasing quartiles of TIR, the prevalence of abnormal ABI decreased.
· Abnormal ABI was negatively correlated with time in range and positively correlated with hypertension, age, diabetes duration, UREA, serum creatinine (Scr), urinary albumin/creatinine ratio (ACR), time above range (TAR), mean blood glucose (MBG), and M values.
· The logistic regression showed a remarkable association between TIR and abnormal ABI, while HbA1C and measures of blood glucose variability had no definite correlation with abnormal ABI.
· There was a significant difference in LDL (low-density lipoprotein) between the low and high ABI groups, and in Scr between the normal and low groups.
· There were significant differences in TIR, age, UREA, ACR, TAR, and MBG between normal and high ABI groups and in diabetes duration between normal and low and normal and high groups.
The findings showed a significant association between low time in range and abnormal ABI values in type 2 diabetes patients after adjusting for cardiovascular risk factors and HbA1C, the traditional gold standard of blood sugar control. This indicates that ABI screening for patients with low TIR values should be stressed in clinical work to recognize high-risk patients for early intervention to improve their clinical outcomes.
"Whether optimized TIR may help to lower abnormal ABI risk and further prevent the advancement of cardiovascular disease and decrease related mortality in patients with type 2 diabetes remains to be proven further by prospective studies," the researchers wrote.
Reference:
Wei, Y., Liu, C., Liu, Y. et al. The association between time in the glucose target range and abnormal ankle-brachial index: a cross-sectional analysis. Cardiovasc Diabetol 21, 281 (2022). https://doi.org/10.1186/s12933-022-01718-y