Although diabetes is characterized by a variety of metabolic derangements, high blood sugar is what defines the disease. In fact, elevated glucose levels serve as the criteria for diagnosing diabetes, even though insulin resistance, systemic inflammation and lipid abnormalities are also integral aspects of this condition. Glucose management remains the keystone of diabetes treatment because elevated blood glucose is what drives the vascular and nerve damage that account for the complications of diabetes.
Advanced Glycation End Products
In type 2 diabetes, high blood glucose is caused by insulin resistance, which prevents the cellular absorption of glucose. In type 1 diabetes, insufficient insulin levels allow your blood glucose to rise too high. In either case, glucose that is not metabolized by your cells is routed into other metabolic pathways. An April 2011 review in "Diabetes Technology and Therapeutics" reports that unmetabolized glucose interacts with tissue and serum proteins, which leads to the creation and accumulation of toxic advanced glycation end products, or AGEs.
Nerve Damage
"The Merck Manual of Diagnosis and Therapy" states that advanced glycation end products, free radicals and sorbitol accumulate in the tissues of diabetic patients. These substances are directly toxic to nerves, especially the small nerves in your hands and feet. They also damage your blood vessels, including those that nourish your nervous system. Diabetic nerve injury, called diabetic neuropathy, first presents as numbness, tingling or burning in your fingers and toes. These sensory deficits gradually advance, involving progressively larger portions of your extremities. Your autonomic nervous system -- the nerves that supply your gut and other internal organs -- is also involved, as are isolated larger nerves throughout your body.
Complications
Diabetic neuropathy results in blunted sensation in your hands and feet. Foot ulcerations and joint damage due to unperceived injuries occur frequently in diabetics. Impaired immunity and poor circulation -- additional complications of diabetes -- lend to the development of intractable infections and, eventually, an increased incidence of amputations. Autonomic neuropathy results in lightheadedness, altered heart rate, impaired digestion and bowel and urinary problems. Involvement of larger nerves leads to sciatica, carpal tunnel syndrome and other symptoms of nerve entrapment.
Considerations
Abnormal glucose metabolism in diabetics leads to the accumulation of advanced glycation end products, sorbitol and other toxic substances that damage nerves and blood vessels. This tissue injury is responsible for many of the complications occurring in diabetic patients, including neuropathy, infections, eye and kidney damage, heart disease and amputations. An April 2011 review in "Diabetes Care" demonstrated that long-term blood glucose control is one key to preventing neuropathy and other diabetic complications. Regular glucose monitoring, daily exercise, dietary management and frequent medical follow-up are essential parts of a diabetic management program.
References
- "Diabetes Technology and Therapeutics"; Advanced Glycation End Products, Measured as Skin Autofluorescence and Diabetes Complications: A Systematic Review; D.C. Bos, et al.; April 2011
- "The Merck Manual of Diagnosis and Therapy, 18th Edition: Diabetes Complications"; Mark H. Beers, M.D., Editor-in-Chief; 2006
- "Diabetes Care"; Protection from Retinopathy and other Complications in Patients with Type 1 Diabetes of Extreme Duration: The Joslin 50-Year Medalist Study; J.K. Sun, et al.; April 2011
