Association between toe brachial index and atherosclerosis in patients with type 2 diabetes mellitus

Objective Measurement of ankle brachial index (ABI) is a simple method of assessing lower limb arterial blood supply,while measurement of toe brachial index (TBI)has only been advocated as an alternative.The aim of this study was to obtain information about whether TBI should be taken in type 2 diabetes,even when ABI is normal,and to evaluate the relationship between TBI and atherosclerosis.Methods In a crosssection study,ABI,TBI,and carotid intimal-medial thickness (IMT) were measured on 979 outpatients with type 2 diabetes in Ruijin Hospital.Those with normal ABI (0.9 ≤ABI ＜ 1.3,n = 945) were divided into two groupsnormal TBI group(TBI≥0.6,n=893) and low TBI group(TBI＜0.6,n=52),and then the clinical and laboratory data were compared between these two groups.Furthermore,the relationship between TBI and atherosclerosis was investigated.Atherosclerosis was defined as the maximum IMT ≥ 1.1 mm.Results Low ABI and low TBI were detected in 1.3% and 6.6% of the patients,respectively.Comparison of the clinical and laboratory data between the two groups showed that age and HbA1C values were significantly higher in the low TBI group.Furthermore,TBI was inversely associated with IMT(β=-0.217,P＜0.01),an indicator for atherosclerosis of the carotid artery.Multiple logistic regression analysis revealed that decline of TBI was an independent risk factor of atherosclerosis (OR=1.30,95% CI 1.01-1.69,P＜0.05).Conclusion In type 2 diabetes,the decline of TBI is associated with atherosclerosis,indicating the necessity for diabetic patients to detect TBI,even when ABI is within normal range,in order to detect peripheral artery disease in early stage,and reduce the risk for atherosclerosis. Key words: Ankle brachial index; Toe brachial index; Diabetes mellitus,type 2; Carotid intimal-medial thickness; Atherosclerosis