Can Motor Nerve Conduction Velocity Predict Foot Problems in Diabetic Subjects Over a 6-Year Outcome Period?

Abstract

OBJECTIVE—This study examined motor nerve conduction velocity (MNCV) and other peripheral nerve and vascular tests as predictors for foot ulceration, amputation, and mortality in diabetes over a 6-year follow-up period. RESEARCH DESIGN AND METHODS—We recruited 169 diabetic subjects (without significant peripheral vascular disease with an ankle brachial pressure index [ABPI] ≥0.75) for the study and separated them into groups (to ensure diversity of nerve function). The control group consisted of 22 nondiabetic people. At baseline, all subjects underwent assessment of MNCV; vibration, pressure, and temperature perception thresholds; peripheral vascular function; and other diabetes assessments. RESULTS—Over the 6-year outcome period, 37.3% of the diabetic subjects developed at least one new ulcer, 11.2% had a lower-limb amputation (LLA) (minor or major), and 18.3% died. Using multivariate Cox’s regression analysis (RR [95% CI] and removing previous ulcers as a confounding variable, MNCV was found to be the best predictor of new ulceration (0.90 [0.84–0.96], P = 0.001) and the best predictors of amputation were pressure perception threshold (PPT) (5.18 [1.96–13.68], P = 0.001) and medial arterial calcification (2.88 [1.13–7.35], P = 0.027). Creatinine (1.01 [1.00–1.01], P < 0.001), MNCV (0.84 [0.73–0.97], P = 0.016), and skin oxygen levels (14.32 [3.04–67.52], P = 0.001) were the best predictors of mortality. CONCLUSIONS—This study shows that MNCV, which is often assessed in clinical trials of neuropathy, can predict foot ulceration and death in diabetes. In addition, tests of PPT and medial arterial calcification can be used in the clinic to predict LLA in diabetic subjects.