Introduction 

Quality of life in diabetic polyneuropathy (DPN) is diminished due to chronic pain symptoms and associated depression. A meta-analysis showed that vitamin B provided inconsistent short-term improvement and was not better than placebo in terms of pain relief. Despite lack of strong evidence for its use and its non-inclusion in treatment guidelines, vitamin B complex has been an important part of peripheral neuropathy treatment.

Aim

To determine the clinical and neurophysiological effects of 1500 μgm/day of oral methylcobalamin (vitamin B12) in diabetic polyneuropathy.

Patient Profile 

Method

Study Design

• Prospective, open label, 24-week trial
• All subjects were given methylcobalamin tablets (500 μgm three times a day) for 24 weeks
• Subjects were clinically assessed periodically at 6, 12, 18 and 24 weeks 

Endpoints

• Primary outcome: decline in Toronto Clinical Scoring System (CSS) post-treatment which indicated improvement
• Secondary outcome: increase in Subjective Impression of Change (SIC) and Clinicians Impression of Change (CIC) and improvement in neurophysiological parameters
• A decrease in Toronto CSS score by ≥2 at 12 and 24 weeks was considered significant

Results 

Efficacy 

• Methylcobalamin treatment was associated with significant progressive decline in the Toronto CSS score (p<0.0001) indicating improvement after the 24-week treatment period (p<0.0001); decline started as early as the 6th week of treatment (p<0.05)
• Improvement with methylcobalamin was observed across all stages of severity (mild, moderate and severe) and in any duration of diabetes whether more or less than 10 years
• Symptoms such as tingling (p<0.03), upper limb symptoms (p<0.003), ataxia (p<0.004), and signs of impaired position sense (p<0.009), vibration sense (p<0.0001), pinprick sensation (p<0.004) and right knee reflex (p<0.004) reversed post treatment if present at baseline; also, if such symptoms were absent at baseline, they did not emerge at the end of the 24-week treatment
• A decrease in frequency post-treatment was highest in symptoms like tingling (48.15%), weakness (42.86%) and pain (36.36%)
• Ulnar nerve amplitude, conduction velocity and distal latency significantly improved post-treatment; however, other secondary outcomes did not improve (p=0.06)

Safety   

Conclusion 

Methylcobalamin 1500 μgm/day decreased the occurrence of the common and disturbing symptoms of diabetic polyneuropathy.

J Diabetes Mellitus 2012; 2(4): 408-412