Impaired vibrotactile sense in children and adolescents with type 1 diabetes - Signs of peripheral neuropathy

Neuropathy in paediatric type 1 diabetes mellitus - clinical characterization and analysis of risk factors in the diabetes prospective follow-up registry DPV (Diabetes-Patienten-Verlaufsdokumentation)-registry

OBJECTIVES

Data on the prevalence, clinical features and risk factors associated with paediatric diabetic neuropathy (DN) are scarce.

METHODS

We retrospectively analysed data from the DPV registry, including patients under 20 years of age, treated for type 1 diabetes mellitus (T1D) between 2005 and 2021. Patients with non-diabetic neuropathy were excluded. Data came from centres in Austria, Germany, Luxembourg and Switzerland.

RESULTS

1,121 of the 84,390 patients included had been diagnosed with DN. Univariate analysis showed patients with DN to be older and predominantly female, with a longer duration of T1D, higher insulin dosages per kg and day, lower rates of insulin pump therapy, higher postprandial glucose-, higher HbA_1c-and higher cholesterol levels, and higher diastolic and systolic blood pressure values. There was also a larger proportion of smokers and higher prevalence of diabetic retinopathy. Median duration of diabetes at diagnosis of DN was 8.3 years. Multivariable analysis, adjusted for demographics revealed an increased risk for DN among female patients and those who were older, underweight (BMI-SDS), smoked cigarettes or had a longer duration of T1D or higher levels of HbA_1c and postprandial blood glucose. The presence of retinopathy and higher cholesterol levels were also linked to increased risk while not-using insulin pump therapy was not.

CONCLUSIONS

DN can develop after just a short duration of T1D. Prevention may be achieved by a lowering of HbA_1c-and postprandial glucose levels through improved glycaemic control. This warrants further investigation. The slight female predominance suggests further hormonal and genetic etiological factors.

Diabetic Neuropathy Assessed with Multifrequency Vibrometry Develops Earlier than Nephropathy but Later than Retinopathy

BACKGROUND

Diabetes is associated with systemic complications. Prevalence of diabetic nephropathy, and retinopathy, in type 1 diabetes mellitus (T1DM) is declining, but it is not known if this is true also for diabetic neuropathy.

AIM

To investigate the relationship between large fibre diabetic neuropathy and other diabetic complications.

MATERIALS AND METHODS

Neuropathy, defined here as large fibre neuropathy, was assessed by measuring vibration perception thresholds at four different frequencies on the sole of the foot, using a standard VibroSense Meter and/or neuropathic symptoms, in 599 individuals with T1DM. Retinopathy status was graded using the International Clinical Disease Severity Scale. Grade of albuminuria and previous history of any macrovascular complications were registered.

RESULTS

Diabetic individuals without retinopathy had similar vibration thresholds as age- and gender-matched control participants without diabetes, whereas those without microalbuminuria had higher thresholds than controls. Two individuals out of 599 (0.3%) had microalbuminuria, but not retinopathy or neuropathy, and 12/134 (9%) without retinopathy had signs of neuropathy. Totally 119/536 (22%) of the patients without microalbuminuria had neuropathy. Vibration thresholds increased with the rising severity of retinopathy and grade of albuminuria. In a multinomial logistic regression analysis, neuropathy was associated with retinopathy (OR 2.96 [1.35-6.49], p=0.007), nephropathy (OR 6.25 [3.21-12.15]; p=6.7×10-8) and macrovascular disease (OR 2.72 [1.50-4.93], p=0.001).

CONCLUSIONS

Despite recent changes in the incidence of diabetic complications, the onset of large fibre neuropathy follows that of retinopathy but precedes the onset of nephropathy in T1DM.

Addressing Chemotherapy-Induced Peripheral Neuropathy Using Multi-Frequency Vibrometry and Patient-Reported Outcomes

(1) The study evaluated correlations between multi-frequency vibrometry (MF-V) and the measure of chemotherapy-induced peripheral neuropathy developed by the European Organization for the Research and Treatment of Cancer (CIPN18). (2) Patients with cancer scheduled to undergo treatment with capecitabine and oxaliplatin (CAPOX) or carboplatin and paclitaxel (Carbo-Tax) were recruited in a prospective, observational study with MF-V and the CIPN18 from baseline to one year after end of treatment. (3) The study recruited 31 evaluable patients. All MF-V measurements correlated significantly with the CIPN18 scores (r = 0.25−0.48, p > 0.003), with a low frequency (32 Hz) from metatarsals showing the best correlation coefficients (0.059 Z-score per CIPN18 point change, r = 0.48, CI-95 = [0.32; 0.60], p > 0.0001). The largest change in MF-V scores from baseline was seen in low-frequency VPTs taken from metatarsals at 8 Hz three months after end of treatment (from −0.26, CI-95 [−0.85, 0.38] to 1.15, CI-95 [0.53, 1.84]) for patients treated with oxaliplatin and at 32 Hz one year after end of treatment (from 0.09, CI-95 [−0.56, 0.77] to 0.88, CI-95 [0.34, 1.47]) for patients treated with paclitaxel. (4) Low-frequency vibration perception thresholds (8 and 32 Hz) correlated better with CIPN18 scores than high-frequency ones (128 and 250 Hz). If validated, this finding will advance CIPN pathophysiological understanding and inform the development of assessment methods.

A systematic review of the prevalence, risk factors and screening tools for autonomic and diabetic peripheral neuropathy in children, adolescents and young adults with type 1 diabetes

AIMS

We aimed to estimate the prevalence of Diabetic peripheral neuropathy (DPN) and Cardiac autonomic neuropathy (CAN) in youth with type 1 diabetes; identify key risk factors; identify the most useful tests for the diagnostic evaluation of DPN and CAN; identify key treatment options for DPN and CAN.

METHODS

A systematic search was performed including studies published in the last 15 years. PICO framework was used in the selection process and evidence was assessed using the GRADE system.

RESULTS

A total of 758 studies were identified and a final number of 49 studies were included in this systematic review. According to moderate-high level quality studies, the prevalence of probable DPN, ranged between 13.5 and 62%; subclinical DPN between 22 and 88%; confirmed DPN between 2.6 and 11%. The Michigan Neuropathy Screening Instrument was the tool with higher sensitivity and specificity for detecting DPN, which needs to be confirmed by nerve conduction velocity. The prevalence of CAN was 4-39%. Specific treatment options for DPN or CAN in patients younger than 25 years are not available. Key risk factors for DPN and CAN are hyperglycemia/HbA1c, age, diabetes duration, the presence of other microvascular complications, waist/height ratio, lipid profile and blood pressure. For CAN, additional risk factors were cigarette smoking, BMI and total daily insulin.

CONCLUSIONS

Prevalence of neuropathy in youth with type 1 diabetes varies depending on different screening methods and characteristics of the study populations. However, the assessed studies confirmed a relatively high prevalence of subclinical neuropathy, reiterating the importance of early identification of risk factors to prevent this complication.

Vibrotactile sense might improve over time in paediatric subjects with type 1 diabetes-A mid-term follow-up using multifrequency vibrometry

AIM

Impaired vibrotactile sense, mirroring diabetic peripheral neuropathy, is present among children and adolescents with type 1 diabetes. This study aims to re-examine the vibrotactile sense of paediatric type 1 diabetes subjects in order to evaluate any alterations in the vibrotactile sense over time.

METHODS

A VibroSense Meter I device was used to determine the vibrotactile perception thresholds (VPTs) for seven frequencies from the pulp of index and little fingers and for five frequencies from metatarsal heads one and five on the sole of the foot, of 37 children and adolescents with type 1 diabetes, previously examined in a larger cohort. Subjects were followed up after a median time of 30 months. Z-scores of VPTs were calculated using previously collected normative data.

RESULTS

Vibrotactile perception thresholds improved over time at low frequencies (especially 16 Hz) on the foot, while not being statistically significant different on the rest of the frequencies, either on hand or foot. VPTs were not correlated with HbA1c.

CONCLUSION

A mid-term follow-up of vibrotactile sense in paediatric subjects with type 1 diabetes shows a conceivable normalization of previously impaired vibrotactile sense on some frequencies on the foot, indicating that vibrotactile sense might fluctuate over time.

Large fibre, small fibre and autonomic neuropathy in adolescents with type 1 diabetes: A systematic review

AIMS

To estimate the prevalence of neuropathy in adolescents with type 1 diabetes.

METHODS

Systematic collection of published studies exploring the prevalence of large fibre neuropathy (LFN), small fibre neuropathy (SFN), and autonomic neuropathy in adolescents with type 1 diabetes. Following prospective registration (Prospero CRD42020206093), PubMed, EMBASE, and Cochrane Library were searched for studies from 2000 to 2020. PICO framework was used in the selection process (Population: adolescents aged 10-19 years with type 1 diabetes; Intervention: diagnostic methods for neuropathy; Comparison: reference data; Outcome: data on prevalence or comparison). Data were extracted concerning study quality based on available data and established methods for determining and diagnosing various neuropathy types.

RESULTS

From 2,017 initial citations, 27 studies (7589 participants) fulfilled eligibility criteria. The study population (47% males) had a diabetes duration between 4.0 and 10.6 years, and HbA1c level between 7.3 and 10.8%, 56-95 mmol/mol. The prevalence of LFN, based on nerve conduction studies, was 10-57%. Based on other tests for neuropathy, the prevalence of LFN and SFN was 12-62%, and that of cardiac autonomic neuropathy was 12-75%.

CONCLUSION

The described prevalence of neuropathy in adolescents with type 1 diabetes varied, which can be methodological due to different screening methods and classifications of neuropathy.

Vibrotactile sense 5 years after carpal tunnel release in people with diabetes: A prospective study with matched controls

AIM

To compare vibrotactile sense, 5 years after carpal tunnel release in people with and without diabetes.

METHODS

Out of 35 people with diabetes and carpal tunnel syndrome, age- and gender-matched with 31 people without diabetes but with idiopathic carpal tunnel syndrome, 27 and 30 people, respectively, participated in this prolonged follow-up. Vibration perception threshold of the index and little finger (median and ulnar nerve, respectively), 5 years after surgery, was measured at seven different frequencies (8, 16, 32, 64, 125, 250 and 500 Hz).

RESULTS

Significant improvement of vibration perception threshold from 1 to 5 years after carpal tunnel release was found at 64 Hz for people with diabetes, while improvement for people without diabetes was demonstrated at several frequencies (64-250 Hz). However, both groups demonstrated a significant decrease in vibration perception threshold for the low frequencies (8-16 Hz). At 5 years, people with diabetes had significantly impaired vibration perception threshold at the index finger for high frequencies (125-500 Hz), and for nearly all frequencies (16 Hz, 64-500 Hz) at the little finger, compared to people without diabetes.

CONCLUSION

After carpal tunnel release, significant mid-term improvement of vibrotactile sense appears limited for people with diabetes, compared to a continuous improvement for people without diabetes. In addition, a decline in low-frequency vibrotactile sense occurs for the median as well as the ulnar nerve innervated fingers. Clinical Trial Registration NCT01201109.

Vibrotactile sensitivity testing for occupational and disease-induce peripheral neuropathies

The International Standard Organization (ISO) standard 13091-1 describes methods and procedures for performing the vibrotactile perception threshold (VPT) testing to diagnose changes in tactile sensory function associated with occupational exposures. However, the VPT test also has been used in the diagnosis of peripheral neuropathies associated with a number of disorders. This review examines the VPT test, variations in procedures that have been used, as well as disorders and diseases in which this test has been reliable for the detection of sensory changes. Mechanisms potentially underlying the changes in VPTs are also discussed along with procedural and subject/patient factors that may affect the interpretation of test results. Based upon the review of the literature, there are also suggestions for where additional research might improve the administration of this test, depending upon the subject/patient population and interpretation of data.

Corneal confocal microscopy identifies a reduction in corneal keratocyte density and sub-basal nerves in children with type 1 diabetes mellitus

PURPOSE

To assess whether alterations in stromal keratocyte density are related to loss of corneal nerve fibres in children with type 1 diabetes mellitus (T1DM).

METHODS

Twenty participants with T1DM and 20 age-matched healthy controls underwent corneal confocal microscopy. Corneal sub-basal nerve morphology and corneal keratocyte density (KD) were quantified.

RESULTS

Corneal nerve fibre density (CNFD) (p<0.001), corneal nerve branch density (p<0.001), corneal nerve fibre length (CNFL) (p<0.001) and inferior whorl length (IWL) (p<0.001) were lower in children with T1DM compared with healthy controls. Anterior (p<0.03) and mid (p=0.03) stromal KDs were lower with no difference in posterior KD (PKD) in children with T1DM compared with controls. Age, duration of diabetes, height, weight and body mass index did not correlate with anterior (AKD), mid (MKD) or PKD. Inverse correlations were found between glycated haemoglobin and PKD (r=-0.539, p=0.026), bilirubin with MKD (r=-0.540, p=0.025) and PKD (r=-0.531, p=0.028) and 25-hydroxycholecalciferol with MKD (r=-0.583, p=0.018). CNFD, CNFL and IWL did not correlate with AKD, MKD or PKD.

CONCLUSION

This study demonstrates a reduction in corneal nerves and anterior and mid stromal KD in children with T1DM, but no correlation between corneal nerve and keratocyte cell loss.

Normative values of the vibration perception thresholds at finger pulps and metatarsal heads in healthy adults

AIMS

To establish normative values of vibration perception thresholds (VPTs), using multi-frequency vibrometry at finger pulps and at metatarsal heads of the foot in healthy adults. We also aimed to investigate factors that could potentially affect VPTs such as age, sex, height, weight, foot- or handedness and skin temperature.

METHODS

VPTs were examined in 924 healthy and randomly selected subjects in the southern Sweden (mean 46 years; 628 women and 296 men). Inclusion criterias were adult subjects (>18 years) in considerable health without diabetes mellitus or other nerve affecting disorders. VPTs were measured at the finger pulps of index and little finger, as well as the first and fifth metatarsal heads of the foot, through multi-frequency vibrometry using the VibroSense Meter® I device. Patient characteristics were recorded and skin temperature was measured before assessment of VPTs.

RESULTS

We present normative values of VPTs for a large population of both male and female subjects in various ages. VPTs detoriated as age increased (0.09-0.59 dB per year; p<0.001), i.e. progressing with normal aging. Increasing skin temperature affected VPTs in finger pulps, but not at metatarsal heads, with -0.2 to -1.6 dB, i.e. vibration perception improved with higher temperatures. Height was only found to affect the VPTs of metatarsal heads (250 Hz: 0.42 dB per cm). Sex, weight and handedness did not affect the VPTs.

CONCLUSION

We investigated the normative values of VPTs and presented affecting factors as age, skin temperature and height. With these results, VPT testing through multi-frequency vibrometry is enabled to be used in a clinical practice as a diagnostic tool when investigating neuropathy and other neurological disorders.

Peripheral and Autonomic Neuropathy Status of Young Patients With Type 1 Diabetes Mellitus at the Time of Transition From Pediatric Care to Adult-Oriented Diabetes Care

INTRODUCTION

The prevalence of neuropathic lesions in young patients with type 1 diabetes mellitus (T1DM) at the time of transition from pediatric care to adult-oriented diabetes care is poorly studied. A comparative study with healthy volunteers to assess the possible neuropathic condition of this special population and to identify the potential early screening needs has not been performed yet. The results may provide important feedback to pediatric diabetes care and a remarkable baseline reference point for further follow up in adult diabetes care.

PATIENTS AND METHODS

Twenty-nine young patients with T1DM [age: 22.4 ± 2.9 years; HbA1c: 8.5 ± 2.1%, diabetes duration: 12.2 ± 5.8 years; (mean ± SD)] and 30 healthy volunteers (age: 21.5 ± 1.6 years; HbA1c: 5.3 ± 0.3%) were involved in the study. Autonomic function was assessed by standard cardiovascular reflex tests. Complex peripheral neuropathic testing was performed by Neurometer^®, Neuropad^®-test, Tiptherm^®, Monofilament^®, and Rydel-Seiffer tuning fork tests.

RESULTS

T1DM patients had significantly higher diastolic blood pressure than controls (80 ± 9 vs. 74 ± 8 mmHg, p < 0.01), but there was no significant difference in systolic blood pressure (127 ± 26 vs. 121 ± 13 mmHg). Cardiovascular reflex tests had not revealed any significant differences between the T1DM patients and controls. No significant differences with Neurometer^®, Neuropad^®-test, and Monofilament^® were detected between the two groups. The vibrational sensing on the radius on both sides was significantly impaired in the T1DM group compared to the controls with Rydel-Seiffer tuning fork test (right: 7.5 ± 1.0 vs. 7.9 ± 0.3; left: 7.5 ± 0.9 vs. 7.9 ± 0.3, p < 0.05). The Tiptherm^®-test also identified a significant impairment in T1DM patients (11 sensing failures vs. 1, p < 0.001). In addition, the neuropathic complaints were significantly more frequently present in the T1DM patient group than in the controls (9 vs. 0, p < 0.01).

CONCLUSION

In this young T1DM population, cardiovascular autonomic neuropathy and cardiac morphological alterations could not be found. However, Rydel-Seiffer tuning fork and Tiptherm^®-tests revealed peripheral sensory neurological impairments in young T1DM patients at the time of their transition to adult diabetes care.

Corneal nerve loss in children with type 1 diabetes mellitus without retinopathy or microalbuminuria

Aims/Introduction

Corneal confocal microscopy is a rapid, non‐invasive ophthalmic technique to identify subclinical neuropathy. The aim of this study was to quantify corneal nerve morphology in children with type 1 diabetes mellitus compared with age‐matched healthy controls using corneal confocal microscopy.

Materials and Methods

A total of 20 participants with type 1 diabetes mellitus (age 14 ± 2 years, diabetes duration 4.08 ± 2.91 years, glycated hemoglobin 9.3 ± 2.1%) without retinopathy or microalbuminuria and 20 healthy controls were recruited from outpatient clinics. Corneal confocal microscopy was undertaken, and corneal nerve fiber density (n/mm²), corneal nerve branch density (n/mm²), corneal nerve fiber length (mm/mm²), corneal nerve fiber tortuosity and inferior whorl length (mm/mm²) were quantified manually.

Results

Corneal nerve fiber density (22.73 ± 8.84 vs 32.92 ± 8.59; P < 0.001), corneal nerve branch density (26.19 ± 14.64 vs 47.34 ± 20.01; P < 0.001), corneal nerve fiber length (13.26 ± 4.06 vs 19.52 ± 4.54; P < 0.001) and inferior whorl length (15.50 ± 5.48 vs 23.42 ± 3.94; P < 0.0001) were significantly lower, whereas corneal nerve fiber tortuosity (14.88 ± 5.28 vs 13.52 ± 3.01; P = 0.323) did not differ between children with type 1 diabetes mellitus and controls. Glycated hemoglobin correlated with corneal nerve fiber tortuosity (P < 0.006) and aspartate aminotransferase correlated with corneal nerve fiber density (P = 0.039), corneal nerve branch density (P = 0.003) and corneal nerve fiber length (P = 0.037).

Conclusion

Corneal confocal microscopy identifies significant subclinical corneal nerve loss, especially in the inferior whorl of children with type 1 diabetes mellitus without retinopathy or microalbuminuria.

Vibrotactile perception on the sole of the foot in an older group of people with normal glucose tolerance and type 2 diabetes

OBJECTIVES

To evaluate vibrotactile sense in an older group of people with normal glucose tolerance and type 2 diabetes relative to other sensory tests.

METHODS

Vibration perception thresholds on the sole of the foot (Multifrequency vibrametry and Biothesiometer) were compared to the results from evaluation of touch (monofilament), electrophysiology (sural nerve) and thermal sensation (Thermotest®).

RESULTS

Vibration perception and temperature thresholds, as well as sural nerve function, differed between normal glucose tolerance and type 2 diabetes. Measuring vibration perception thresholds at lower frequencies with multifrequency vibrametry versus biothesiometer provided correlations similar to sural nerve amplitude. Temperature thresholds correlated with vibration perception thresholds and sural nerve function. Monofilaments revealed pathology in only a few participants with type 2 diabetes.

CONCLUSIONS

In an older group of people, vibration perception thresholds show a correlation similar to sural nerve amplitude on tactile and non-tactile surfaces. Measuring a vibration perception threshold on a tactile surface in type 2 diabetes provides no clear advantage over measuring it on the medial malleolus. In older type 2 diabetes subjects, both large and small diameter nerve fibers are affected.

Examining practice effects in repeated measurements of vibration perception thresholds on finger pulps of healthy individuals - Is it possible to improve your results over a clinically relevant test interval?

Aims

To investigate practice effects in a test-retest situation, where vibration perception thresholds (VPT) were measured in healthy subjects using a multi-frequency test method.

Methods

In eight consecutive tests, VPTs were tested in the pulps of the index and little fingers at seven frequencies (8, 16, 32, 64, 125, 250 and 500 Hz). Subjects were twenty healthy adults aged 26 to 65 years (mean 46.0 ± 11.1 years; 10 male and 10 female). The subjects were examined at six tests with intervals of one month (mean 33 ± 6; time 0 to month 5) and at two additional tests with prolonged intervals (month 12 and 18). Linear mixed model analysis was performed to investigate differences over the subsequent test occasions. To examine where potential practice effects occurred, a pairwise comparison with Bonferroni correction was made.

Results

Small decreases in VPTs were found in 8 out of the 14 frequencies (index finger: 8, 16, 32, 250 and 500 Hz; little finger: 16, 250 and 500 Hz) within the test period from time 0 to month 5. In tests at 12 and 18 months, VPTs were increased compared to month 5, but lowered in comparison with time 0. Hence, minor significant decreases were found in three frequencies for the index finger (125, 250 and 500 Hz) and one frequency for the little finger (250 Hz) when examining VPTs with prolonged time intervals.

Conclusions

When evaluating vibration perception thresholds in a clinically relevant time period of once or twice a year, no consideration of practice effects is necessary when interpreting the results.

Peripheral nerve disease secondary to systemic conditions in children

This review is an overview of systemic conditions that can be associated with peripheral nervous system dysfunction. Children may present with neuropathic symptoms for which, unless considered, a causative systemic condition may not be recognized. Similarly, some systemic conditions may be complicated by comorbid peripheral neuropathies, surveillance for which is indicated. The systemic conditions addressed in this review are critical illness polyneuropathy, chronic renal failure, endocrine disorders such as insulin-dependent diabetes mellitus and multiple endocrine neoplasia type 2b, vitamin deficiency states, malignancies and reticuloses, sickle cell disease, neurofibromatosis, connective tissue disorders, bowel dysmotility and enteropathy, and sarcoidosis. In some disorders presymptomatic screening should be undertaken, while in others there is no benefit from early detection of neuropathy. In children with idiopathic peripheral neuropathies, systemic disorders such as celiac disease should be actively excluded. While management is predominantly focused on symptomatic care through pain control and rehabilitation, some neuropathies improve with effective control of the underlying etiology and in a small proportion a more targeted approach is possible. In conclusion, peripheral neuropathies can be associated with a diverse range of medical conditions and unless actively considered may not be recognized and inadequately managed.

Strong association between vibration perception thresholds at low frequencies (4 and 8 Hz), neuropathic symptoms and diabetic foot ulcers

Aims

To investigate whether multi-frequency measurement of vibration perception thresholds (VPTs) can identify individuals with a high risk of developing diabetic foot ulcer or neuropathic symptoms.

Methods

VPTs were measured at six different frequencies (4, 8, 16, 32, 64 and 125 Hz) on metatarsal heads 1 and 5 on the sole of the foot using a standard VibroSense Meter device in 535 type 1 diabetic (T1DM) patients and 717 non-diabetic control subjects. VPTs in control subjects were used to establish normal values for five different age groups for male and female subjects respectively. Normal values were defined as a VPT below the mean plus 1.66 x standard deviation for each group. Various definitions of abnormal VPTs were tested using either all frequencies, only lowest VPT frequencies (4 and 8 Hz) or only highest VPT frequencies (64 and 125 Hz).

Results

The VPTs were higher in T1DM patients than in non-diabetic control subjects matched for age and gender. The low frequencies, 4 and 8 Hz, particularly were associated with the risk of diabetic foot ulcer (OR 40.7 [5.4–308.4], p = 0.0003) and with difficulties in balance and or gait (OR 1.89 [1.04–3.46], p = 0.04) difficulties and weakness (OR 2.77 [1.25–6.16], p = 0.01). The VPTs at the 125 Hz frequency were higher in short duration (≤ 10 yrs.) T1DM patients compared to age- and gender-matched control subjects.

Conclusions

Vibration perception thresholds at low frequencies seem to be a better indicator of the risk of developing diabetic foot ulcers, gait or balance problems or weakness of the foot. The 125 Hz frequency, however, seemed to be impaired earlier and it was the only pathological VPT frequency in patients with short duration of diabetes.This study suggests that at least four different frequencies (4, 8, 64 and 125 Hz) should be included in any examination in order to obtain a complete evaluation of the risk factors for diabetic neuropathy and diabetic foot ulcers.