We value the comments of Williams, Norman, and Stacey (1) in their letter regarding our article (2) on the comparative roles of microvascular and nerve function in foot ulceration in type 2 diabetes. We agree that ankle brachial pressure indexes (ABPIs) should be interpreted with caution in people with diabetes, as medial calcification is common. However, Brooks et al. (3) have shown that toe brachial pressure index does not convey any advantage over ABPI in determining perfusion pressure of the lower limbs except in those with overt calcification, i.e., an ABPI >1.3. We were thus careful not to include any subjects with ABPI >1.3. Moreover, if there were subjects with peripheral vascular disease in the ulcer group, it would have lowered the microvascular response, whereas our study demonstrated no difference. In fact, there were slightly higher responses in those with ulceration. Thus, the key finding of our study was that microvascular studies may not differentiate between people with and without foot ulceration.
As described in our article (2), diabetic subjects were recruited consecutively from the outpatient clinic. The diabetic groups had higher BMIs compared with the control group. We would remind the correspondence that the important comparison was between the diabetic groups. There was no difference in BMI between the diabetic groups, and, thus, BMI would not influence the findings. Again, with regards to age, there was no statistically significant difference between the diabetic groups.
In those diabetic subjects with an active ulcer, the laser studies were performed on the contralateral foot; thus, there was no influence of local inflammation on the microvascular studies. As suggested, the effect of vasoactive medication on maximum blood flow is minimal, and, moreover, similar numbers of subjects in the two groups were on medication for cardiovascular protection.
We believe that our study design and methodology are robust and conclude that these microvascular tests may not be of additional value in discriminating those with and without ulceration. However, we agree with the correspondents that microvascular dysfunction may play a role in delayed wound healing, as stated in our article.
