Diabetes mellitus has become a modern global epidemic, with steadily increasing prevalence rates related to lifestyle such that 27% of individuals aged 65 years or older have diabetes mellitus, 95% of whom have type 2. This article reviews the effects of diabetes mellitus on the neuromuscular system.
Diabetes mellitus leads to diverse forms of peripheral neuropathy as the major neuromuscular complication. Both focal and diffuse types of neuropathy can develop, with the most common form being diabetic sensorimotor polyneuropathy. Small fibers are damaged early in the development of diabetic sensorimotor polyneuropathy and are not assessed by nerve conduction studies. Small fiber damage occurs even in the prediabetes stage. No disease-modifying therapy for diabetic sensorimotor polyneuropathy is available at this time, but this complication can be limited in patients who have type 1 diabetes mellitus with strict glycemic control; the same outcome is not clearly observed in patients who have type 2 diabetes mellitus. Recently, the evidence base for symptomatic treatments of painful diabetic sensorimotor polyneuropathy underwent systematic review. Effective evidence-based treatments include some anticonvulsants (eg, pregabalin, gabapentin), antidepressants (eg, amitriptyline, duloxetine), opioids (eg, morphine sulfate, oxycodone), capsaicin cream, and transcutaneous electrical nerve stimulation.
This article reviews the increasing prevalence of diabetes mellitus and diabetic sensorimotor polyneuropathy and discusses recent consensus opinion on the objective confirmation needed for the diagnosis in the clinical research setting. The evidence from clinical trials shows that intensive glycemic control reduces prevalence of diabetic sensorimotor polyneuropathy in patients with type 1 diabetes mellitus, but variable outcomes are observed in patients with type 2 diabetes mellitus. Finally, despite the lack of disease-modifying treatment, effective evidence-based therapy can control painful symptoms of diabetic sensorimotor polyneuropathy.
Address correspondence to Dr Vera Bril, Toronto General Hospital, 200 Elizabeth St, 5EC-309, Toronto, ON M5G 2C4, Canada, firstname.lastname@example.org.
Relationship Disclosure: Dr Bril has received grant support and personal compensation for consultancy work from Dainippon Sumitomo Pharma Co, Ltd; Eisai, Inc; Eli Lilly and Company; Pfizer Inc; and Grifols, Canada, Ltd. Dr Bril has also received grant support from Cebix Incorporated, CSL Behring, and Novartis Corporation, as well as unrestricted educational fellow support from Grifols, Canada, Ltd.
Unlabeled Use of Products/Investigational Use Disclosure: Dr Bril discusses the unlabeled use of gabapentin, amitriptyline, morphine, and oxycodone for the treatment of neuromuscular complications of diabetes mellitus.