The aim of the present study is to assess before, as well as 6 and 12 months following a therapy with benfotiamine the influence of therapy on intraepidermal nerve fiber density (skin biopsy) and neuropathic symptoms and deficits in people with type 1 or 2 diabetes mellitus and diabetic sensomotoric neuropathy.

Inclusion Criteria:

• Have type 1 or type 2 diabetes mellitus based on the disease diagnostic criteria (WHO) classification on ongoing insulin or/and oral antidiabetic therapy with a stable regimen for the previous 3 months
• Male or female subjects aged between 18 and 75 years, inclusive
• Have an HbA1c level ≤ 9.5% without optimizing potential
• mTCNS (modified Toronto Clinical Neuropathy Score) ≥ (above or equal to) 6) OR (a score on the MNSI (Michigan Neuropathy Screening Instrument)questionnaire of ≥4 or a score on the MNSI examination ≥2.5)
• Medical history without major pathology (with the exception of type 2 diabetes) as judged by the investigator, especially no major peripheral artery disease.
• Body mass index (BMI) between 25 and 45kg/m2, both inclusive

Exclusion Criteria:

• Subjects with secondary forms of diabetes such as due to pancreatitis.
• Current or previous treatment (less than 6 months) with benfotiamine, B-vitamins, vitamin B complex, alpha lipoic acid or actovegin.
• Have any contraindications, known allergy, or hypersensitivity to benfotiamine.
• Have any contraindications, known allergy, or hypersensitivity to local anesthetics.
• Neuropathy by other origin than diabetes.
• Other severe pain that might impair the assessment of neuropathic pain.
• Treatment with more than one of following: tricyclic antidepressants, serotonin norepinephrine reuptake inhibitors, anticonvulsants, class I antiarrhythmics with Na-channel inhibition (mexiletine, flecainid, propafenon and others) or neuroleptics in patients receiving these drugs for neuropathic pain.