Carnitine therapy for insulin resistance and diabetes (part 2)

An inexpensive supplement: image from Anabol Naturals

Carnitine has been of interest to diabetes doctors and researchers for some time. Indeed a search of the National Library of Medicine using the terms “carnitine” and “diabetes” brings up papers from 50 years ago. The prevailing opinion from 50 years of metabolic biochemistry is that when we eat more fat than our fat cells can store, it leads to the accumulation of partially metabolized fat molecules which find their way into muscle. There, they activate a signaling pathway that just happens to turn down the sensitivity of the insulin signal. Thus unmetabolized inappropriately stored fat molecules may directly cause insulin resistance.

Perhaps the strongest evidence for carnitine’s role in helping to promote glucose disposal was a series of elegant studies performed about 15 years ago in which healthy or diabetic volunteers were set up with an IV such that researchers could introduce glucose directly into the subject’s blood stream. Glucose levels were kept constant throughout these experiments (this is called a “glucose clamp” experiment). By keeping track of the amount of glucose that needed to be introduced into the blood stream to maintain constant blood glucose the researchers were, in effect, measuring glucose utilization in these people. What they found was that in infusion of carnitine produced an increase in glucose utilization. In other words, the subjects became better able to metabolize glucose. 

We can make carnitine but it is estimated that about 75% of our carnitine reserve comes from our diet. Carnitine is mostly stored in muscle tissue (meat) which means that vegetarians do not take in dietary carnitine. However, a healthy vegetarian diet is low fat and therefore vegetarians require much less carnitine.

The problem arises from our processed food culture. These foods are high in fat but have no carnitine. Thus a lifetime of eating processed foods can leave us (like those rats - see part 1 of this article) with a carnitine deficit. Luckily for us, carnitine is available as a supplement. Body builders like using carnitine because it increases muscle mass. Supposedly, it also decreases hunger so it may play a role as a diet aid. Most importantly, no toxicities have been reported (that I know of) suggesting that non-prescription use of this substance is relatively safe.

Should you take carnitine? If you have type 2 diabetes you are insulin resistant. IF (and ONLY if) your doctor is ok with it, I think it is worth a shot. Should your insulin resistance abate because of the additional carnitine you will find that you need less insulin to control your blood sugar. The danger would be hypoglycemic episodes. Be sure to keep a sugar source close by as hypoglycemia while driving a car could be deadly. Interactions of carnitine with other common diabetes medications have not been examined so, again, talk to your doctor first. If you are inclined to try it out, Dr. Mynatt has proposed a dose of 3 grams per day based on his preclinical studies. The question that sticks in my mind is whether carnitine would synergize with exercise…hmmmmm.

To learn more about carnitine here are some resources:

A good scientific review: “Diabetes and Carnitine” by Randall Mynatt.

An informative web site: ods.od.nih.gov/News/Carnitine_Conference_Summary.aspx