Sunday Nov 10, 2013 (foodconsumer.org) -- A new study in Endocrinology suggests that taking amino acid L-arginine as a dietary supplement may help improve glucose tolerance in patients with diabetes mellitus.

Karen Ryan from the University of Cincinnati in Cincinnati, Ohio and colleagues conducted the study and found supplementation of L-arginine increased plasma glucagon-like peptide 1 and insulin, and substantially improved glucose clearance in both lean and obese mice.

It has been known that drugs that can increase glucagon-like peptide 1 (GLP-1) can also improve glucose homeostasis in type 2 diabetes mellitus.  The current study was intended to test and see if L-arginine, which is a known insulin secretagogue, can promote the production of GLP-1 and increase postprandial insulin secretion and improve glucose tolerance.

For the study, both lean and obese mice were given L-arginine before an oral glucose tolerance test and tested for plasma GLP-1, insulin and glucose clearance after the glucose challenge.  Oral L-arginine supplementation was found to increase plasma GLP-1, insulin and drastically improve glucose clearance.

The researchers also found GLP-1 receptor (GLP-1R)-signaling is important for these benefits provided by L-arginine.  Mice without GLP-1R did not respond to the L-arginine supplement while mice with this receptor when exposed to L-arginine gained increased levels of GLP-1 and insulin and had improved glucose tolerance.

The study concluded "These findings raise the intriguing possibility that l-arginine-based nutritional and/or pharmaceutical therapies may benefit glucose tolerance by improving the postprandial GLP-1 response in obese individuals."

The study suggests that L-arginine supplements may be enlisted to help patients with type 2 diabetes mellitus to manage their postprandial blood sugar.

Arginine supplementation has been known for long to help type 2 diabetes mellitus.  A study published in 2001 in Diabetes Care revealed that long term oral L-arginine supplementation improve peripheral and hepatic insulin sensitivity in patients with type 2 diabetes mellitus.

PierMarco Piatti, MD from Università Vita-Salute, IRCCS H. San Raffaele and colleagues let 12 lean type 2 diabetic patients use L-arginine in a dose of 3 grams per time three times per day for two months.  Prior to the treatment, patients were treated with their usual diet for one month.  Ten patients were using placebo for the same period.  Before and after the supplementation, glucose disposal was measured.

L-Arginine supplementation was found to increase blood flow and glucose disposal when the patients underwent the glucose challenge.  But arginine could not completely restore peripheral and hepatic insulin sensitivity in type 2 diabetic patients to a normal level.

L-arginine is an amino acid which is found high in peanuts.   Arginine is found important in helping cardiovascular health and male reproductively, in addition to other health benefits.  It is available as a dietary supplement on the Internet and local health stores. (David Liu, PHD)