TYPE 2 DIABETES FATTY MUSCLE Skeletal muscles are the large muscle groups, such as the biceps, triceps, quadriceps, trunk and gluteal muscles, that we use to move our limbs voluntarily.
This differentiates them from smooth muscles-muscles such as the hearth or diaphragm-which is largely not under voluntary control. Skeletal muscles burn the bulk of the glucose available after meals and store their own supply of glycogen to provide quick bursts of energy. This muscle glycogen is not available for use by other organs of the body. Normally, little fat is found in skeletal muscle. Fat cells are specialised for fat storage; muscle cells are not.
With hyperinsulinemia and excess sugar, the liver creates new fat by DNL and distributes these triglycerides throughout the body. When adipocytes (fat storage cells) become overwhelmed, skeletal muscles also take up the fat, leading ultimately to fat deposits between muscle fibers. The technical term is intramyocyte lipid accumulation, but it could easily be called fatty muscle.
Process of developing fatty muscle
We can see the process of developing fatty muscle more clearly in farm-raised cattle, where the accumulation of fat are clearly visible as marbling-the intermingling of fat with lean muscle. As the meat cooks, the fat melts, making the beef more tender, moist, and flavourful, as it literally bastes itself. For this reason, well-marbled beef commands a premium price. Kobe beef, the ultra-premium Japanese delicacy, is prized for its high degree of marbling. The United States Department of Agriculture grades beef based on the degree of marbling.
Cattle ranchers know that marbling depends almost entirely on diet. Cows are ruminants, which means they normally eat grass and do not develop marbling. The result is a more flavourful but less tender steak. However, a grain-heavy diet increases the growth rate as well as the marbling. For this reason, many grass-fed cows are “finished” with a period of corn feeding to develop the desired fatty muscle, or marbling. Carbohydrate-heavy diets cause fatty muscle. It’s no secrete in cattle, and it works just as well in humans.
TYPE 2 DIABETES FATTY MUSCLE
Fatty liver produces insulin resistance in the liver. In the same manner, fatty muscle produces insulin resistance in skeletal muscles. Hyperinsulinemia forces too much fat and glucose inside the skeletal muscles. They become completely full, so insulin cannot push any more inside. This is the same overflow phenomenon. Since the skeletal muscles are so large, they contribute significantly to overall insulin resistance in the body.
Fat deposition in skeletal muscles, obesity, and severity of insulin resistance are closely related. Muscles from obese subjects take up fatty acid at an equal rate to lean subjects but burn it at only half the speed, leading to greater accumulation of fat within the muscles. Weight loss can partially rectify this problem.
Why can’t the muscle just burn off this fat? The answer lies in the biochemical process known as the Randle cycle. A little bit about the Randle cycle in next post.
Also, read Type 2 Diabetes Fatty Liver