Medial arterial calcification (MAC) commonly occurs in diabetes mellitus. A high ankle brachial index (ABI) is a validated marker for its presence, but its clinical significance is not well delineated.   The aim was to determine the clinical characteristics of patients with an abnormal ABI.

After ethics approval,a retrospective chart review was performed for patients attending the Prince of Wales Hospital Diabetes Centre,over a 2 year period. Statistical analysis was performed using SPSS.

 307 cases were analysed. The mean age of the whole cohort was 64.8 years. Those with highest quartile ABI had a longer duration of diabetes, and were older in comparison to those with mid quartile ABI groups(68.7±9.1 years vs61.5±12.3 and 62.5±1.1 years).Occurrence rates of peripheral neuropathy, ulceration and osteomyelitis,were significantly higher in the lowest and highest quartiles, compared to the middle quartiles

 There was no significant difference in HbA1c, or total cholesterol across quartiles of ABI. BMI did not differ across quartiles however waist was higher in highest ABI quartile as compared to mid quartile range(110.7±13.3cm vs 103.5±15.6cm and 103.9±14.7cm).There was a positive linear correlation between ABI and waist. Serum eGFR differed across quartiles of ABI , but there was no difference in serum calcium.phosphate product across the ABI groups.

 Both higher and lower ABI are associated with adverse clinical events, and the presence of peripheral neuropathy is not unique to high ABI. Waist showed a linear relationship with ABI suggesting a role for visceral adiposity in the pathogenesis of MAC.  An inverse relationship has also been recently demonstrated for adiposity and markers of bone turnover. We hypothesise that that insulin resistance may contribute to the low bone turnover state characteristic in diabetes mellitus when there is mineral deposition in vascular tissue. Future prospective studies of MAC would benefit from evaluation of markers of bone turnover.