By Charlie Rumrill, V Form

Type 2 Diabetes as a Global Epidemic

Type 2 Diabetes mellitus is a group of chronic disorders caused by either the number of pancreatic beta-cells, their ability to function, or the skeletal muscle and liver cells ability to transduce insulin’s signal, all of which result in hyperglycemia. Due to genetic, environmental, and epigenetic factors, Type 2 Diabetes has rapidly become a global epidemic. 

In order to understand the pathophysiology, or diseased state, of Type 2 Diabetes, a comprehension of how the body typically regulates carbohydrate metabolism is required. As shown in figure 1, the catabolism, or breakdown, of carbohydrates begins as soon as it is ingested, with salivary amylase enzymes hydrolyzing the large polysaccharides into smaller oligosaccharides. When the salivary mixture is swallowed, it continues through the esophagus to the stomach which denatures the enzymes with its highly acidic environment. Since no enzymes can function in the stomach, the digestion of the carbohydrates temporarily stops until it continues to the small intestine, where more amylase enzymes produced by the acinar cells in the pancreas meet the fluid in the small intestine and continue to hydrolyze the oligosaccharides into simpler disaccharides. As the mixture continues through the small intestine, brush border cells with enzymes attached hydrolyze the disaccharides into simpler monosaccharides, such as glucose. Only now can the once large polysaccharides be absorbed into the bloodstream. From the small intestine, the blood circulates directly to the pancreas, where the pancreatic beta-cells secrete insulin due to the elevated blood-glucose levels. Then, the blood flows to the liver and the rest of the body (Figure 1) where the liver and skeletal muscle cells bind to insulin, triggering more glucose transporters to be embedded in the cellular membrane. Due to the cells having more transporters, more glucose molecules can enter the cell, and the glycogen phosphorylase enzymes can bind them together through dehydration synthesis to form glycogen. Insulin also travels to the adipose tissue, where the glucose is then stored as fats. In addition to the effects of insulin, glucose molecules are constantly being taken into every cell in order for it to have the energy to complete its functions. Over time, due to the glycogen being produced and cells constantly needing glucose the body’s blood-glucose levels then lower.  When the blood-glucose levels decrease, the pancreatic alpha-cells secrete the hormone glucagon which, when bound with the skeletal muscle and liver cells, triggers the glycogen to be hydrolyzed and released back into the bloodstream as glucose.