Initial findings in the relationship between diabetic peripheral neuropathy and microvascular reactivity in the foot
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Authors: Barwick,A.;Tessier,J.;Janse De Jonge,X.;Chuter,V.
Start Page: S502
Background and aims: Microvascular dysfunction is common in people with diabetes resulting in diabetic nephropathy, retinopathy and neuropathy of both the large and small fibre nerves. In the periphery it contributes to diabetic ulceration via both peripheral neuropathy and changes to microvascular function. Post-occlusive reactive hyperaemia is a measure of microvascular reactivity (vasodilation capacity) that has been implicated in the diabetic foot complications. This study aimed to investigate the relationship between large and small fibre neuropathy and the postocclusive reactive hyperaemia response in the diabetic foot.
Materials and methods: Diabetic participants were recruited from podiatry clinics for this cross-sectional study. They underwent testing for large fibre neuropathy (vibration perception threshold and monofilament detection), small fibre neuropathy (temperature and pain perception) as well as post occlusive reactive hyperaemia at the hallux (using laser Doppler). Correlations between presence of large and small fibre neuropathy, postocclusive reactive hyperaemia parameters (time to peak and peak as a % of baseline) and demographics characteristics including sex, HbA1c, age, height, weight and duration of diabetes were performed. Binary logistic regressions were performed on factors associated with the presence of large fibre neuropathy and small fibre neuropathy.
Results: Eighty-eight participants were included in the analysis. Significant but weak correlations were observed between presence of large fibre neuropathy and age (r=0.20; p<0.05), height (r=-0.35.; p<0.05), and time to peak (r=-0.21; p<0.05). Correlations were observed between small fibre neuropathy and height (r=0.34; p<0.05), and time to peak (r=0.24; p<0.05). Binary logistic regression analyses demonstrated presence of large fibre neuropathy was associated with several demographic factors including increasing age (OR of 1.08 (95%CI: 1.02-1.15, p<0.05) and greater height (OR of 1.1 (95%CI: 1.04-1.15, p<0.05) and time to peak perfusion after occlusion (OR of 1.02 (95%CI: 1-1.04, p<0.05). Presence of small fibre neuropathy in taller people (OR of 1.09 (95%CI of 1.03-1.15, p<0.05) and those with an increased time to peak perfusion after occlusion (OR1.02, 95%CI 1-1.03).
Conclusion: Greater height is associated with increased likelihood of the presence of both large and small fibre peripheral neuropathy. An increased time to peak following occlusion was also associated with increased likelihood of both types of neuropathy suggesting microvascular dysfunctionmeasured by post occlusive reactive hyperaemia (specifically increased time to peak) is associated with higher likelihood of the presence of peripheral neuropathy.