Endocrine Abstracts

Purpose: To determine the proportion of abnormal current perception threshold (CPT) in patients with type 2 diabetes mellitus.

Methods: A total of 1360 patients with type 2 diabetes mellitus involved in an epidemiological study received an examination of CPT measured by Neurometer® CPT/C (Neurotron, Inc., Baltimore, Maryland, USA) on a supine position. The measurement was taken for three frequencies, i.e., 5, 250 and 2000 Hz at three sites: the preauricular area (trigeminal nerve), the index finger (median nerve) and the great toe (superficial peroneal nerve) on both sides. The three frequencies measure small unmyelinated C fiber (5 Hz), small myelinated Aδ fiber (250 Hz), and large myelinated Aβ fiber (2000 Hz), respectively. The normative data from 75 normal individuals were used as control and an “abnormal CPT” was defined as a value greater than the normal mean plus 3 standard deviations derived from the normal individuals. Age, sex, body height and body weight were treated as potential confounders. Student’s t test, Chi-square test, correlation coefficient and stepwise regression were used for statistical analyses and a P value <0.05 was considered as statistically significant.

Results: Accept for a significantly older age in the diabetes group, the distribution of sex, body height and body weight were not different significantly. CPT measurements on the right and left sides correlated significantly with correlation coefficients mostly >0.7 (P<0.0001) in the diabetes patients. The trigeminal nerve had the most commonly reported “abnormal CPT” that involved approximately 60% of the diabetes patients, followed by the superficial peroneal nerve (50%) and the median nerve. The median nerve showed frequency-dependent abnormality with higher proportion of “abnormal CPT” involving lower frequency. For the frequency of 2000, 250 and 5 Hz, “abnormal CPT” was observed in 15–20, 30–33 and 56–59%, respectively. In stepwise regression analyses, diabetes and age were consistently predictive for CPT.

Conclusions: Patient with type 2 diabetes mellitus have higher CPT values than normal individuals in all anatomical sites. The application of Neurometer® for screening of diabetes neuropathy awaits further confirmation.