L-arginine's effect on type 2 diabetes

Sensitive Side

Sometimes you find a gem buried in the mud.

That’s what happened today when I was doing some background research for a study of L-arginine (also known simply as arginine) that showed how dietary intake of this amino acid might be effective in lowering C-reactive protein levels and reducing heart disease risk.

That study is certainly of interest, but the details don’t quite have the legs to support an entire e-Alert. Fortunately I stumbled across another arginine study, and although it’s a few years old (from 2001), it offers valuable information for anyone with type 2 diabetes or a pre-diabetic condition.

Gaining control

In several e-Alerts and HSI Members Alerts we’ve told you about the remarkable benefits of arginine, known to reduce inflammation, repair skin and connective tissue, and regulate the thymus gland. Arginine is also a precursor of nitric oxide, an essential compound and neurotransmitter that promotes blood circulation by dilating vessels and stimulates secretion of insulin.

As reported in the journal Diabetes Care, a team of researchers from the UK and Italy mounted a study to examine the effect of arginine on insulin sensitivity.

The subjects included 12 type 2 diabetics with an average age of 58. None of the subjects were overweight and their only treatment for diabetes was diet modification. Ten non-diabetics served as control subjects, participating only in the testing portion of the study.

The 12-week study was divided into two phases. In phase one, subjects simply continued their normal diets for one month. In the second phase, subjects were randomly divided into two groups. One group remained on their diet and received a placebo for two months. The other group did the same for one month, but in the final month the placebo was replaced with an arginine supplement: three grams, three times each day. Insulin sensitivity was monitored throughout the study.

Analysis of the data showed a four percent increase in insulin sensitivity in the control group, compared to a 34 percent increase in the arginine group. And although the arginine didn’t completely resolve insulin sensitivity issues, the change was a significant improvement. The arginine group as a whole also experienced a decrease in systolic blood pressure.

Working around meals

L-arginine’s dietary sources include dairy products, meat, poultry and fish, as well as nuts, rice, whole-wheat, soy and raisins. It can also be taken in supplement form, available in most health food stores and through Internet sources.

If you talk to your doctor and decide that arginine supplements might help your insulin management, here are two supplementing tips from HSI Panelist Allan Spreen, M.D.:

“In my opinion it is correct that arginine (or ornithine, or l-tryptophan, or l-carnitine, or whatever, if it’s an amino compound) should not be taken with a protein meal. There are a limited number of receptors for protein substances (protein foods are composed of amino acids), so the supplement you paid good money for will be ‘diluted’ by the presence of other proteinaceous substances in the digestive neighborhood. That is not true of most other supplements, which should be taken with food.

“For serious users I go with 1000 milligrams twice/day to three times/day between meals, and I’ve found that most of the amino supplements work better with some degree of exercise.”

We first told you about L-arginine in the April 2001, issue of the HSI Members Alert in an article about citrulline, an important amino acid that acts as a catalyst for the manufacture of L-arginine. Citrulline also has cardioprotective effects, but is specifically known for helping patients overcome physical exhaustion and mental fatigue.

In that Members Alert we also mentioned a unique product called Citrudex that combines citrulline with a natural component of apples called malate, which enhances the work of the amino acid. You can find more information about Citrudex at the Center for Natural Medicine Online Pharmacy (cnm-inc.com).

And one last note for those who are dieting and exercising; arginine has also been shown to facilitate muscle metabolism by reducing body fat while increasing muscle mass.


The complaint department is open at the FDA.

According to a USA Today article published earlier this month, reports on drug side effects and drug-related health problems hit an all-time high last year – more than 422,000 – up almost 14 percent over the total complaints reported in 2003.

Why the jump in adverse event reports? That depends on who you talk too.

An FDA official named Paul Seligman told USA Today that more drugs on the market and a surge in drug use probably account for the rise. (Drug sales in 2004 exceeded sales in 2003 by a little over eight percent.)

Sidney Wolfe, M.D., director of the Health Research Group for the advocacy organization Public Citizen agreed with Mr. Seligman’s assessment, but added that greater awareness of the problems associated with prescription drugs may play an important role as well. Dr. Wolfe told USA Today that the public has become much more knowledgeable about “drug-induced disease.”

What a concept! Drug-induced disease. This could be the dawn of an exciting new field of medicine: Doctors who only treat diseases caused by prescription drugs.

Mr. Seligman noted that there was no “unusual acceleration” of reports in the last quarter of 2004. So even though the controversy over prescription painkillers like Vioxx and Celebrex hit the fan late in the year, this apparently didn’t “spur a rush of new concerns.”

No rush of new concerns? I don’t agree. From what I heard, people who used those painkillers were extremely concerned, not to mention bewildered and probably a little angry. Mr. Seligman seems to be confusing “concerns” with actual “reports of side effects.”

If the FDA invited consumers to voice their concerns they’d need to staff a 24-hour hotline.

To Your Good Health,

Jenny Thompson
Health Sciences Institute


“Long-Term Oral L-Arginine Administration Improves Peripheral and Hepatic Insulin Sensitivity in Type 2 Diabetic Patients” Diabetes Care, Vol. 24, No. 5, May 2001, care.diabetesjournals.org

“Arginine Boosts Insulin Sensitivity and Cardiovascular Function” Life Enhancement, life-enhancement.com

“Drug Complaints Reach Record High” Kevin McCoy, USA Today, usatoday.com