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Insulin and GLUT4

Insulin and GLUT4 are both responsible for transporting glucose into the cells for energy. Many of us don't really know what GLUT4 is, but we've all heard of insulin at one time or another. Don't feel bad, I had never heard of it either until I did a ton of research about diabetes and how glucose is cleared.

What is GLUT4?

GLUT4 means glucose transport type 4. There are other types, but GLUT4 is the most abundant and most responsible for transporting glucose. Its function is increased by both insulin and muscle contractions. It's stored mainly in adipose tissue and striated skeletal muscle.

Expression of GLUT4

GLUT4 expression happens primarily through muscle contractions. Insulin and GLUT4 both transport glucose into muscles as glycogen. As muscles contract, like in resistance training, GLUT4 and insulin are expressed at much higher rates than at rest.

Endurance training

Some studies have shown that endurance training can actually reduce glucose uptake into the muscles, except in high-intensity type training. Endurance type training, including things like cardio, involves the body using type 1 (slow-twitch) muscle fibers. Endurance training still uses glucose for energy but when muscle glycogen levels are depleted, GLUT4 function can be reduced and hypoglycemia can occur. This is why many endurance athletes participate in carb-loading the day before a race. They consume a lot of carbohydrates to load up on and store glycogen for the race the next day.

Resistance training

Resistance training can be the most effective way to clear glucose out of the bloodstream by means of the GLUT4 transporter molecule.1 You may have heard me say many times over that resistance training has had the biggest impact on my glucose levels.

Diet and GLUT4

It's no secret that both diet and exercise increase insulin sensitivity. There are some diet and supplement options that increase GLUT4 activity as well. Creatine is a popular bodybuilding supplement that is backed by over 500 studies. It's proven to be very safe and one of the few supplements that actually work. It benefits everyone from bodybuilders to athletes to regular people who are just getting into fitness. In people with diabetes, and everyone else, creatine boosts GLUT4 activity.

I've been taking creatine for 2 years now. To be honest, I discovered the glucose-lowering effects by accident. I was taking it for weight lifting purposes and noticed it had a big impact on glucose when I took it for workouts, or at any other time. You can get creatine from food as well, like: meats, milk, and especially watermelon. Watermelon is high in creatine but also high in sugar.


While resistance training appears to have a greater effect on blood glucose, it's important to have a well-rounded workout regimen. Before starting, stopping, or changing any workout activity, or making changes to your diet, please consult your healthcare professionals and please be safe.

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