Ratio of waist-to-calf circumference and carotid atherosclerosis in Korean patients with type 2 diabetes

OBJECTIVE

To investigate whether waist circumference (WC), calf circumference (CC), and waist-to-calf ratio (WCR) are associated with carotid atherosclerosis in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This was an observational study performed in 3,694 Korean patients with type 2 diabetes. Anthropometric measures and carotid ultrasound were performed on each subject. Carotid atherosclerosis was defined as having a clearly isolated focal plaque or mean carotid intima-media thickness (CIMT) ≥1.1 mm.

RESULTS

CIMT and the frequency of carotid atherosclerosis were higher with increasing WC quartiles and decreasing CC quartiles. There was an augmentative effect of CC and WC on the frequency of carotid atherosclerosis, which was dramatically higher in both the highest WC quartile and lowest CC quartile. However, except for the relationship between the quartile of CC with the frequency of carotid atherosclerosis in men, those associations disappeared after adjusting for potential confounders. In contrast, WCR was significantly related to CIMT (only in women) and carotid atherosclerosis, even after adjustment (adjusted odds ratio for carotid atherosclerosis for the highest quartile of WCR compared with the lowest quartile being 1.178 [95% CI 1.026–1.353] and 1.276 [1.053–1.545] in men and women, respectively).

CONCLUSIONS

A low CC and high WC seems to be associated with a carotid atherosclerotic burden in Korean diabetic patients. In particular, compared with each circumference, WCR is independently associated with carotid atherosclerosis. However, the cross-sectional nature of the study limits conclusions regarding the direction or causality. Further longitudinal study is warranted in this and other ethnic groups.Obesity is an important risk factor for a broad spectrum of cardiometabolic disturbance, including hypertension, dyslipidemia, glucose intolerance, and even cardiovascular disease. In particular, abdominal obesity is more closely associated with risk of disease than general obesity. Waist circumference (WC) or waist-to-hip ratio (WHR), as indicators of abdominal obesity, may be better predictors of the risk of disease than the BMI, an indicator of general obesity (1,2). In contrast, leg muscle mass and peripheral adiposity might offer protection from cardiometabolic diseases. Larger hip or thigh circumferences seem to be associated with a lower risk of type 2 diabetes and a decreased risk of developing coronary artery disease and premature death (3–5). Recent evidence that calf circumference (CC) is also associated with mortality or cardiovascular risk is growing (6–8).Considering that the effects of abdominal fat and leg lean mass on the risk of diseases are diametrically opposed, indices that assess both masses simultaneously may be better at evaluating the risk for cardiometabolic disease compared with indices that separately estimate either abdominal fat or leg lean mass. In that sense, the WHR or waist-to-thigh ratio (WTR) may be better than other simple anthropometric indices, and some studies have suggested that both indices are more sensitive than WC at estimating cardiometabolic risk (9–11). However, it is not practical to use those two indices in a busy clinical practice. In particular, the WHR may mask the accumulation of abdominal fat if the hip circumference is also increased (12).In this study, we measured WC and CC to evaluate abdominal fat and leg lean mass and used the waist-to-calf ratio (WCR) as an index to assess the disproportion between abdominal fat and leg muscle mass. The aim of the current study was to investigate whether WC, CC, and WCR are associated with carotid atherosclerosis in a large cohort of patients with type 2 diabetes.