Diabetes mellitus, commonly referred to as diabetes, is one of the world's fastest growing chronic diseases and was the seventh leading cause of death in the U.S. in 2006. It is characterized by an inability to regulate the levels of glucose in the body, leading to high blood sugar. Metabolic regulation of glucose is a complex process involving a variety of different hormones and it is the breakdown of this regulation that leads to diabetes.
Symptoms of Glucose Imbalance
The major signs of high blood sugar are the need to urinate frequently, increased thirst and fluid intake and increased appetite. The body responds to high glucose levels in the blood by excreting excess glucose in the urine. This will cause dehydration, leading to thirst and increase fluid consumption. Patients presenting with these symptoms will have their blood glucose levels analyzed by their doctor.
Normal Glucose Metabolism
Blood glucose concentration is determined by the body's ability to balance the volume of glucose entering the system and the rate of glucose removal. Glucose entering the blood stream comes from three sources: absorption through the gut during feeding, the breakdown of glycogen in the liver and the breakdown of fat and protein during fasting. These processes are under the control of several hormones, including insulin, glucagon, amylin, glucagon-like peptide 1, glucose-dependent insulinotropic peptide, epinephrine, cortisol and growth hormone. When the body is functioning properly, these hormones work to maintain glucose at healthy levels by excreting it when it is not needed, storing it when required or breaking down the body's reserves when starved.
Glucose Metabolism in Diabetes
Diabetes is characterized by high blood sugar. This is caused by the body's inability to produce enough insulin, as in type 1 diabetes, or by a failure of the body's cells to respond to the insulin that is produced, as in type 2 diabetes. Insulin is produced in response to feeding and its main function is to promote glucose removal from the blood stream. It does this by promoting cellular uptake of glucose, as well as signaling to the liver to cease glucose production through the breakdown of glycogen and instead promote glycogen synthesis. In diabetes, a lack of insulin or insulin resistance will lead to the breakdown of this regulation, causing high blood sugar. Treatment is focused on correcting this imbalance and will depend on the type of diabetes the patient is suffering from.
Treatments to Correct Glucose Metabolism
As type 1 diabetes is caused by the death of insulin-producing cells, sufferers have to receive insulin, usually through injection. Type 2 diabetes is more complicated and treatment is targeted towards particular patient needs. Many type 2 patients can improve through diet and exercise alone. Drugs that treat type 2 diabetes are targeted towards reducing glucose absorption, promoting insulin secretion and stopping glucose production by the liver. Some type 2 diabetes patients may also require insulin to control their blood sugar.
Effects of Prolonged Glucose Metabolism Defects
Elevated glucose levels from poorly managed or untreated diabetes will lead to a number of medical complications, including diabetic neuropathy, diabetic retinopathy and an increased risk of cardiovascular disease. Both diabetic neuropathy and retinopathy are linked to blood vessel damage caused by high glucose levels. In the case of diabetic neuropathy, blood vessels supplying the nerves are injured, leading to a loss in sensation in peripheral regions, such as the feet. This can lead to increased injury and infection, sometimes leading to ulceration and, in extreme cases, amputation. Diabetic retinopathy is triggered by damage to the microvasculature of the retina, which, if left untreated, can lead to impaired vision and, eventually, blindness.
