Content area
Full text
OBJECTIVE-To evaluate mechanisms underlying diabetic neuropathy progression using indexes of sural nerve morphometry obtained from two identical randomized, placebo-controlled clinical trials.
RESEARCH DESIGN AND METHODS-Sural nerve myelinated fiber density (MFD), nerve conduction velocities (NCVs), vibration perception thresholds, clinical symptom scores, and a visual analog scale for pain were analyzed in participants with diabetic neuropathy. A loss of ≥500 fibers/mm^sup 2^ in sural nerve MFD over 52 weeks was defined as progressing diabetic neuropathy, and a MFD loss of ≤ 100 fibers/mm^sup 2^ during the same time interval as nonprogressing diabetic neuropathy. The progressing and nonprogressing cohorts were matched for baseline characteristics using an O'Brien rank-sum and baseline MFD.
RESULTS-At 52 weeks, the progressing cohort demonstrated a 25% decrease (P < 0.0001) from baseline in MFD, while the nonprogressing cohort remained unchanged. MFD was not affected by active drug treatment (P - 0.87), diabetes duration (P = 0.48), age (P = 0.11), or BMI (P = 0.30). Among all variables tested, elevated triglycerides and decreased peroneal motor NCV at baseline significantly correlated with loss of MFD at 52 weeks (P = 0.04).
CONCLUSIONS-In this cohort of participants with mild to moderate diabetic neuropathy, elevated triglycerides correlated with MFD loss independent of disease duration, age, diabetes control, or other variables. These data support the evolving concept that hyperlipidemia is instrumental in the progression of diabetic neuropathy. Diabetes 58:1634-1640, 2009
Twenty-three million Americans have diabetes, and the incidence is increasing by 5% per year. The most common complication of diabetes is peripheral neuropathy, occurring in -60% of all diabetic patients (1-3). In the U.S., diabetic neuropathy is the leading cause of diabetes-related hospital admissions and nontraumatic amputations (1-3). Current methods used to confirm diabetic neuropathy and measure its progression include presence of symptoms, clinical signs, deficits in nerve conduction studies (NCVs), and quantitative sensory measures (1-3). Changes in these parameters correlate with anatomical evidence of decreased large and small myelinated fiber densities (MFDs) in the sural nerve (4,5) and the epidermis (intraepidermal nerve fiber density) (6). Although several risk factors for diabetic neuropathy are identified in prior randomized or observational clinical trials (7,8), a comprehensive understanding of their relationship and relevance for risk assessment is still lacking.
Diabetic neuropathy is positively correlated with the most common marker...