06/13/2015    Allen Jacobs, DPM

Neuropathy Due to Vitamin B-12 Deficiency, Not Diabetes

Dr. Udell appropriately indicates that the
ordering vitamin B12 levels may be appropriate in
the patient with diabetes. Several other factors
should be considered.

Vitamin B 12 deficiency is commonly encountered
in diabetic patients not taking metformin. Jawa,
et al. (endocrine practice, 16, 2010 ) noted in
their study that as many as 48% of patients with
diabetes not taking metformin demonstrate low
levels of vitamin B 12 and that B12 deficiency is
common in the diabetic patient. Carnell (clinical
nutrition 94, 1 2011 ) addressed the possible
unreliability of serum vitamin B12 levels in the
diabetic patient. He noted that cobalamin
deficiency is common, but that many cases are
subclinical and that vitamin B12 testing may be
unreliable in the diabetic patient.

Furthermore, Solomon (Diabetes Care, 34, 5, 2011
) noted that some patients have a functional B 12
deficiency. In these patients vitamin B12 levels
are normal however, markers for vitamin B 12
deficiency such as elevated methylmalonic acid
levels are noted. Furthermore, vitamin B12
deficiency may exist even in patients who are
large consumers of vitamin B12, and that
macrocytosis is not a reliable marker for vitamin
B12 deficiency. (Wycliffe et al no of clinical
nutrition, 86, 4, 2007 ).

Vitamin B12 is required for normal nerve
function. In addition, vitamin B12 is required in
order to prevent accumulation of Homocysteine .
Elevated levels of Homocysteine are associated
with increased risk of diabetic neuropathy as
well as vascular thrombosis.

The active form of vitamin B12 has been available
as one of the agents in Metanx. More recently,
"me too" neuropathy supplements advocated for the
treatment of diabetic neuropathy have added B12
to their formulation.

As I have always had an interest in diabetic
neuropathy, and have had involvement as a speaker
and researcher for for Metanx, I have long had an
appreciation for the role of B12 in diabetic
neuropathy. Although much attention has been
directed to the active form of folic acid, L-
methyl folate, and its role in the management of
diabetic neuropathy, from a personal view I have
always been respectful of the data supporting the
additional therapeutic benefit of vitamin B12 in
management of diabetic neuropathy.

It has been no surprise to me that other agents
touted for the treatment of diabetic neuropathy
have now added vitamin B 12 to their formulation.

It should also be recalled that literature exists
to suggest that vitamin D also plays a
significant role in the development of diabetic
neuropathy when present in inadequate amounts.

Allen Jacobs, DPM, St. Louis, MO

There are no more messages in this thread.