Does instantaneous blood glucose affect vibration perception threshold measurement using biothesiometer?

Nociception at the diabetic foot, an uncharted territory

The diabetic foot is characterised by painless foot ulceration and/or arthropathy; it is a typical complication of painless diabetic neuropathy. Neuropathy depletes the foot skin of intraepidermal nerve fibre endings of the afferent A-delta and C-fibres, which are mostly nociceptors and excitable by noxious stimuli only. However, some of them are cold or warm receptors whose functions in diabetic neuropathy have frequently been reported. Hence, it is well established by quantitative sensory testing that thermal detection thresholds at the foot skin increase during the course of painless diabetic neuropathy. Pain perception (nociception), by contrast, has rarely been studied. Recent pilot studies of pinprick pain at plantar digital skinfolds showed that the perception threshold was always above the upper limit of measurement of 512 mN (equivalent to 51.2 g) at the diabetic foot. However, deep pressure pain perception threshold at musculus abductor hallucis was beyond 1400 kPa (equivalent to 14 kg; limit of measurement) only in every fifth case. These discrepancies of pain perception between forefoot and hindfoot, and between skin and muscle, demand further study. Measuring nociception at the feet in diabetes opens promising clinical perspectives. A critical nociception threshold may be quantified (probably corresponding to a critical number of intraepidermal nerve fibre endings), beyond which the individual risk of a diabetic foot rises appreciably. Staging of diabetic neuropathy according to nociception thresholds at the feet is highly desirable as guidance to an individualised injury prevention strategy.

High prevalence of diabetic neuropathy in population-based patients diagnosed with type 2 diabetes in the Shanghai downtown

AIMS

To determine the prevalence of diabetic peripheral neuropathy (DPN) and risk factors associated with DPN in type 2 diabetic patients.

METHODS

435 diabetic patients were evaluated on complete foot examination. Body mass measurements, resting blood pressure, fasting blood measures, urinary albumin-to-creatinine ratio (ACR) and the digitally stored fundus images were investigated.

RESULTS

(1) The prevalence of DPN was 61.8% among the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown, 59.1% with vibration perception threshold > or =25 V and 13.8% with inability to feel the monofilament. (2) DPN was significantly associated with age (beta: 0.068, S.E.: 0.013, OR: 1.070, CI: 1.043-1.098, P<0.001) and HbA1c (beta: 0.224, S.E.: 0.081, OR: 1.251, CI: 1.067-1.466, P=0.006) by a logistic regression analysis. (3) The percentage of diabetic retinopathy (DR) in the DPN group (26.5%) was significantly higher than that in the non-DPN group (15.2%). (4) The percentage of macroalbuminuria in the DPN group (9.0%) was significantly higher than that in the non-DPN group (1.8%).

CONCLUSIONS

The prevalence of DPN observed in the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown reached up to 61.8% though the observations in our study might be representative of the diabetic patients of the Shanghai downtown.

Vibration perception threshold and the law of mobility in diabetic mellitus patients

BACKGROUND

Diabetic neuropathy is a family of nerve disorders with progressive loss of nerve function in 15% of diabetes mellitus (DM) subjects. Vibration Perception Threshold (VPT) is one of the modalities of testing loss of protective sensation. Law of mobility for VPT is well known for normal subjects, but not for diabetic subjects. This is a pilot study to evaluate and plot the law of mobility for VPT among DM subjects.

METHODS

We used biothesiometer to find the VPT of several areas in upper and lower extremities for normal and diabetic subjects. VPT of normal and diabetic subjects for different foot areas from proximal to distal is evaluated for 30 subjects. All the subjects are screened for peripheral artery occlusive disease with ankle brachial pressure index (0.9 or above). VPT values of different areas are arranged in a proximal to distal order for the analysis.

RESULTS

VPT values monotonically decrease from proximal to distal areas. Vierodt's law of mobility holds well for normal subjects in both feet areas. The law of mobility does not hold good for the DM subjects in one or both feet areas.

CONCLUSIONS

The VPT value of diabetic subjects reveals that the law of mobility do not holds good for diabetic subjects in foot areas. Though the number of subjects is small, all the subjects defied the law.