Introduction

Neuropathy is one of the most common long-term complication of diabetes which affects about 50% of diabetic patients. 1  Neuropathy is strongly associated with the duration and severity of yperglycemia.
Distal symmetrical polyneuropathy is the most common type of diabetic neuropathy and accounts for 75% of diabetic neuropathies. Painless paresthesia with impairment of vibration, joint position, touch and pressure sensations along with loss of ankle reflex is the characteristic feature of distal symmetrical polyneuropathy.2
Biothesiometer can quantify & pick up early cases of DPN & is an important  diagnostic tool in clinical practice3. Principle is a vibrating probe, vibration amplitude can be changed by voltage adjustment. Biothesiometry is used in diagnosis  of peripheral neuropathies with impaired vibratory perception threshold, mainly in diabetology and neurology.
Diagnosis
A crucial aspect of diagnosing diabetic neuropathy entails ruling out other etiologies for
neuropathic pain 4

Diagnostic Criteria for Clinical Diagnosis of DPN
Young et al.5 criteria for clinical diagnosis of DPN (NSS + NDS Score > 8) can be used as bed side tool .
NSS (Neuropathy Symptoms Score) is  burning, numbness or tingling, fatigue, cramping, aching, or nocturnal exacerbation &  NDS (Neuropathy Disability Score) is calculated by ankle reflex, pinprick sensation, temperature sensation, vibration sense tested with tunning  fork and monofilament test.

Aims & objectives

This study was planned to validate the NSS+NDS  as per “Young  et al” criterion in clinical diagnosis with the standard well validated screening method of measuring vibration perception threshold (VPT) with a biothesiometer in middle aged people with Diabetes  where foot care practices are scantly followed
Secondary aim of this study was to find co-association of DPN thus diagnosed(NSS+NDS Bed side evaluation ) with other diabetic complications

RESEARCH DESIGN AND METHODS

855Type –2 diabetes patients who got newly enrolled at “North Delhi Diabetes Centre,Rohini, New Delhi” between July 2011 to June 2012 were evaluated clinically by neuropathy symptom score (NSS) & Neuropathy Disability score (NDS) as suggested by “Young et al’5. Peripheral Neuropathy was diagnosed clinically if sum of NDS + NSS was > 10

135 patients out of total 855 patients who had NSS  5-6 (mild symptoms) or NDS  5-6 but if sum of NDS + NSS was > 10  were then evaluated by biothesiometry to validate this score . VPT> 15 volts was taken as cut off for mild DPN & VPT >25 volts was considered as significant DPN. 
Detailed Diabetes Profile including their clinical profile namely Age, Sex, Mean duration of Diabetes, their personal habits smoking, dietary habits were evaluated.  These patients were also evaluated for presence of Microabluminuria, Retinopathy, PVD and Dyslipidaemia etc.

RESULTS

86 patients had monofilament impairment, 49 patients had normal monofilament test.
96 patients were detected to have DPN by VPT   (60 severe, 36 mild to Moderate)
Hence, applying NDS+NSS >10 as per ” Young et al criterion “ could pick up early DPN in 96 out of 135 ( sensitivity of 71.1% & specificity of 90%  ) This has a +ve predictive value of 57.14% & --ve predictive value of 94.32%  as validated & documented   by biothesiometer .
Prevalence of DPN in total 855 patients evaluated clinically by NSS & NDS later tested by biothesiometry was found to be 15.4 %.
Mean FBS in the study group was 153.8 + 11.0 mg % as compared to  136.4 + 18.2 mg% in the comparison group . Mean PPBS was 231.9 + 17.4 mg %  in the study group while PPBS in the comparison group was 194.7 + 25.4 mg . So on multiple regression analysis.  DPN was associated with poor glycemic control in the study group.
DPN also  had a strong co-association with other complications like DR (44.1% Vs 19.2 %) and Microalbuminuria 61.3 % Vs 38 % on multiple regression analysis.

Table 1

Demographic Characteristics

Table 2

Complications

Table 3

Results

Discussion

About  one third of diabetic people are at risk of foot ulceration because of loss of protective sensation  due to peripheral  Neuropathy .The symptoms of neuropathy & the conventional assessment of it with Cotton wool,   Vibrating tuning fork, pin prick and hot and cold sensation can give a qualitative diagnosis.
Diabetic neuropathy increases the risk of myocardial infarction and reduces the life span, resulting in death of 25–50% of patients within 5–10 years of disease existence 2  As per our own study 6, diabetic peripheral neuropathy (DPN) has strong co-association with other complications such as diabetic retinopathy (67% vs 21.2%) and micro albuminuria 51% vs 41%. It was also observed that 56% patients with DM of less than 5 years had moderate/severe DPN
Large-fiber dysfunction, as measured by vibration perception threshold (VPT), predicts foot ulceration, lower-limb amputation, and mortality (7-9). Early in the natural history of DPN, patients are usually asymptomatic. Thus, reliable identification of individuals in the early stages of the neuropathic process is required so that more rigorous modification of risk factors and foot care education can be implemented. The best method to identify such patients is still a matter of some debate (10-13)
A number of approaches are available for the diagnosis of diabetic neuropathy . Sensory examinations and electrophysiological  measurements  include the evaluation of muscle power, sensations of pinprick, position of joints, touch, and temperature. These tests may lack adequate sensitivity in early stages of neuropathies due to scarce demyelination of neurons.4  Hence, Neurological examination like NSS & NDS can be an important bed side  tool in the clinics for early diagnosis of DPN ).
Our study  has used VPT of >15 as early DPN & > 25 mV as the significant DPN for the diagnosis of neuropathy and the prevalence of peripheral neuropathy was 15.4 per cent. The use of VPT for the diagnosis of neuropathy has been well validated by clinical studies with a sensitivity and specificity of 80 and 98 per cent respectively14. This is further substantiated by large epidemiological prospective studies showing that a VPT more than 25 mV had a sensitivity of 83 per cent, a specificity of 63 per cent, a positive likelihood ratio of 2.2 (95% CI, 1.8-2.5), and a negative likelihood ratio of 0.27 (95% CI, 0.14-0.48) for predicting a foot ulceration over 4 years15.
86 patients in our study  had monofilament impairment, 49 patients had normal monofilament test.  96 patients were detected to have DPN by VPT   (60 severe, 36 mild to Moderate)
Hence, applying NDS+NSS >10 as per ” Young et al criterion “ could pick up early DPN in 96 out of 135 ( sensitivity of 71.1% & specificity of 90%  ) This has a +ve predictive value of 57.14% & --ve predictive value of 94.32%  as validated & documented   by biothesiometer . Prevalence of DPN in total 855 patients evaluated clinically by NSS & NDS later tested by biothesiometry was found to be 15.4 %.

Conclusions

Management of neuropathic complications in diabetes poses significant clinical challenge.
Symptomatic treatments are beneficial but may be insufficient.
These complications severely affect the quality of life in patients especially in late stages. Early screening and diagnosis of neuropathic complications assumes crucial importance.
Neurological examination like NSS & NDS can be an important bed side  tool in the clinics for early diagnosis of DPN with a sensitivity of 71.1% & specificity of 90% . It is simple , acceptable, reproducible & validated as per our study .
DPN was associated with poor glycemic control in the study group & has a strong co-association with other complications like DR (44.1% Vs 19.2 %) and Microalbuminuria 61.3 % Vs 38 %