Prevalence of neuropathy in type 2 diabetic patients and its association with other diabetes complications: The Verona Diabetic Foot Screening Program

Abstract

Aims

Somatic neuropathy is a chronic complication of diabetes. The purpose of our study was to determine prevalence and clinical variables associated with somatic neuropathy applying a simple screening method.

Methods

All outpatients with type 2 diabetes attending our diabetic clinic were offered to participate into a diabetic foot screening program, in the period January 2004–December 2012. A total of 3,591 diabetic patients (55.5% men, age 68 ± 10 years) underwent detection of somatic neuropathy using the Michigan Neuropathy Screening Instrument in its parts of symptoms (administering a questionnaire) and clinical assessment slightly modified (evaluating foot inspection, vibration sensation by biothesiometer, ankle reflexes).

Results

The prevalence of somatic neuropathy was 2.2% in men and 5.5% in women (p < 0.001) when assessed by symptom questionnaire, whereas it was 30.5% in men and 30.8% (p = NS) in women when identified by clinical assessment. In subjects with somatic neuropathy macro- and microvascular complications of diabetes were significantly more common. In multivariate logistic regression analyses BMI, HbA1c and ankle/brachial index independently predicted the presence of neuropathy.

Conclusion

The prevalence of somatic neuropathy in type 2 diabetes is nearly 30% when searched with clinical examination. Poor metabolic control, excess body weight and peripheral arteriopathy are independent markers of somatic neuropathy.

Introduction

Diabetic somatic neuropathy is a chronic complication of diabetes which can lead to major morbidities such as the diabetic foot. Manifestations range from subclinical to clinically evident alterations. Detection may rely on symptoms, abnormal physical examination, quantitative sensory testing, electrodiagnostic procedures and other more complex tools (American Diabetes Association and American Academy of Neurology, 2010). The most common among diabetic neuropathies is the peripheral sensorimotor form, that is symmetrical, chronic and length-dependent (Tesfaye et al., 2010). The prevalence of diabetic neuropathy varies widely based on instruments and criteria adopted to make the diagnosis (Dyck and Dyck, 1999, Dyck et al., 1993, Fedele et al., 1997, Stratton et al., 2004, The DCCT Research Group, 1988, Young et al., 1993).

Electromyography, electroneurography and sural nerve biopsy represent the gold standard in detecting diabetic somatic neuropathy, after exclusion of other causes. Skin biopsy has also been proposed as a reliable surrogate tool (Lauria & Lombardi, 2007). However, all these approaches are restricted to selected patients as they are not suitable for use in large epidemiological studies, because they are time-consuming, patient-unfriendly, costly, and need to be performed by an expert. Under normal circumstances the screening is based on symptom questionnaires and/or on physical assessment looking for signs suggesting or documenting the presence of neuropathy (Perkins & Bril, 2003). One of the most widely used tool is the Michigan Neuropathy Screening Instrument (MNSI, originally proposed in 1994) validated contra a quantitative neurological examination coupled with nerve conduction studies (Feldman et al., 1994). The MNSI includes a questionnaire of symptoms and a brief clinical examination involving: foot inspection (for deformities, dry skin, callus, infection, ulceration), semiquantitative assessment of vibration sensation at the dorsum of the great toe by a 128 Hz tuning fork, grading of ankle reflexes. This approach has been applied in a large multicenter Italian trial (5) and in the DCCT/EDIC study (Herman et al., 2012).

This study, performed in a large sample of type 2 diabetic patients, aimed to estimate: 1) the prevalence of somatic neuropathy with a largely applicable tool; 2) the association of neuropathy with clinical parameters; 3) the relation of neuropathy with chronic diabetes complications.