Background
The burden of Type 2 Diabetes (T2DM) is rising equally in rural and urban India.  Distal Peripheral Neuropathy (DPN) is the most prevalent chronic debilitating complication of T2DM. Loss of Protective sensation due to DPN is the main risk factor for amputation in patients with T2DM. Estimated prevalence of neuropathy has varied greatly in Indian studies (8% to 59%) depending on the method used, population screened and sample size. The state of Kerala in south India, despite having reported prevalence of T2DM as high as 20% (1), studies estimating prevalence of peripheral neuropathy in T2DM from the state are very few.

Aim
To establish the prevalence and associates of Distal Peripheral Neuropathy in patients with Type 2 Diabetes attending a multispecialty hospital in South Kerala.

Method
A cross-sectional study of 671 consecutive patients with T2DM was performed at the Outpatient Diabetes Clinic of a multispecialty hospital in Pathanamthitta district of South Kerala. Relevant history, clinical examination, laboratory tests were obtained from all patients. Patients with features suggestive of neuropathy due to alternate causes were excluded. Assessment for DPN was done by measuring Vibration Perception Threshold (VPT) using a biothesiometer, a well validated method. Peripheral Arterial Disease (PAD) was evaluated by measuring Ankle Brachial Index. Average VPT of more than 25V measured by a single observer was defined as presence of DPN. Data collected based on a questionnaire was entered into Microsoft Excel. Statistical analysis including descriptive statistics and Chi- square test for categorical data was done using SPSSv15.  

Results
Of the 671 patients, 40.1% were males. Mean age was 59.96 ± 9.19 years. 67.5% of patients had BMI more than 25kg/m2. Duration of T2DM was less than 10 years in 36.1%. 40% had duration of diabetes more than 15 years. Mean HbA1c was 8.3±1.52%. HbA1c was more than 8% in 54.7%.

The overall prevalence of DPN in this population was 45.8%. Evidence of Cardiovascular disease (CVD - Coronary Artery Disease, Stroke or TIA) was seen in 32.6%. Prevalence of retinopathy was 25.5%, increased Urine Albumin Excretion Rate (UAER) was 34.1% and PAD was 10.7%. eGFR (CKD-EPI) was more than 60 mL/min/1.73m2 in 80%. Insulin was used by 48.6% of patients. 40.4% had their latest FBS less than 130mg/dL, while only 25.2% had their 2 hour PPBS below 180mg/dL. 81.2% were on statins and 52.2% were on antiplatelets.

Presence of DPN was associated with increasing age (p<0.001). 17.1% of patients below 50 years of age and 70.6% above 65 years had DPN. DPN was present in 27.3% patients less than 10 years duration and 56.2% of those having more than 15 years duration of T2DM(p<0.001). Presence of DPN was strongly associated with CVD including PAD (p<0.001), retinopathy (p<0.001) and insulin use (p<0.001), after adjusting for age, duration of diabetes and HbA1c. In patients above 50 years of age presence of DPN was associated with increasing height of the individual (p<0.001). In patients with diabetes duration less than 10 years, DPN was associated with higher HbA1c levels (P=0.013). In patients with duration of diabetes more than 10 years, presence of DPN had significant associations with low eGFR (p<0.001), increased UAER (p<0.001), elevated systolic blood pressure (p=0.027). No significant association was observed with sex, BMI, smoking, dyslipidemia. 

Discussion
The prevalence of DPN in patients with T2DM is very high in this population. To our knowledge, this is the first study from Kerala to estimate prevalence of DPN in T2DM. Our results are in concordance with similar studies from other regions of India and abroad.  The study reaffirmed that poor glycemic control during early part of diabetes is a risk factor for DPN. The association between CVD and DPN shown by Brownrigg et al is observed in our study(2). Early onset of T2DM, improved healthcare delivery and increasing longevity in Kerala mean that the prevalence of DPN is rising. An increased awareness of the high prevalence of DPN, especially in older patients, should result in improved screening programs at primary care level in order to reduce the high incidence of neuropathic diabetic foot ulceration. 

References:
1.Unnikrishnan R, Anjana RM, Mohan V, Diabetes mellitus and its complications in India:Nature Reviews Endocrinology 12,357–370(2016)

2.Brownrigg JRW, de Lusignan S, McGovern A, et alPeripheral neuropathy and risk of cardiovascular events in type 2 diabetes mellitusHeart 2014;100:1837-1843

High prevalence of peripheral neuropathy in type 2 diabetes: a hospital based cross sectional study from South India