Effects of Benfotiamine on Intraepidermal Nerve Fiber Density (IENFD)

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.