A recent presentation at the AADE meeting suggests that a combination of a plant-based diet plus vitamin B12 may help a common form of painful diabetic neuropathy called distal symmetric polyneuropathy (DPN).
DPN is common in people with diabetes, and is usually attributed to long-term poor diabetes control – but it may also have additional causative factors including (among others) alcohol abuse, neurotoxic medications, and vitamin B12 deficiency. These should be investigated, and if present, treated. If no other factors are found, then the standard treatments for peripheral neuropathy should be tried: tighten up the control of diabetes, topical creams such as capsaicin, and oral medications including antidepressants, anticonvulsants and opioids. Some newer drugs are specifically approved for treatment of diabetic nerve pain, including Cymbalta (duloxetine), Lyrica (pregabalin), and Nucynta (tapentadol).
But the standard medications for DPN are less-than-perfect, so alternative approaches have been tried, including dietary manipulations. The present study, A Dietary Intervention for Chronic Diabetic Neuropathy (AKA the "DINE" study) falls into this category, and was a small -- but provocative -- study.
In a randomized controlled 20-week trial with 35 T2D patients with painful neuropathy, half the patients were assigned to follow a meal plan, as well as taking a daily vitamin B12 supplement, while the other half of the subjects only took the B12 supplement, without any dietary instruction and with a request to not make major dietary changes. The dose of B12 was 1000 mcg/day.
The assigned meal plan for the diet-plus-B12 group mandated plant-based foods only (AKA "vegan diet"), and was low-fat (3 g per serving or 20-30 g/day), with suggestions that it be high-fiber (40 g/day) and low glycemic index. There were no portion limits. There were weekly classes, with "nutrition education, social support, cooking demonstrations, [and] food product sampling."
Food records showed that 13 of the 17 diet-group participants were fully compliant with the vegan diet. The diet-plus-B12 group showed improvement in A1C, reduced diabetes medications in 10 of the 17 (compared to 2 of 18 B12-only participants), and showed "significantly greater improvements" in reported pain, using several methods of assessing pain, including pain questionnaires and galvanic skin response testing. The authors point out that the weekly meetings motivated the patients, and one might assume that, as a result, these patients were more compliant with other aspects of their diabetes care plan such as glucose monitoring, medication-taking, etc. However, if one can discount the Hawthorne effect (the phenomenon whereby people improve as a response to the increased attention of participating in a research study), it would appear that a plant-based meal plan plus vitamin B12 might have been helpful.
Clearly, a larger and longer trial, with groups with and without B12 supplementation, and with a control group that also has weekly support and diet-education meetings (of course without focusing on plant-only foods) is worthwhile.
In the meantime, if you have DPN, should you try a plant-based meal plan? Perhaps. I don't see any particular reason not to do so. But be sure to discuss the concept with your physician, and plan to review your meal plan with your diabetes educator or dietitian before starting.