Glucose and oxygen together in cells are two of the body's primary sources of energy. Glucose concentrations in the blood are maintained within a normal range for a given person. Concentrations of glucose below the set range result in an energy deficit. Symptoms may included fatigue, lightheadedness and, if extreme, coma and death. Excessive glucose damages proteins. Proteins provide vital structural and functional support to the body. Because excess glucose, also known as hyperglycemia, can be so detrimental, its causes are an important matter.
Drugs
Certain drugs are associated with hyperglycemia. Corticosteroids such as prednisone are used to suppress the immune system and can cause hyperglycemia. Beta blockers such as propranolol, used to lower heart rate and blood pressure, also can raise blood glucose. Another class is the thiazide diuretics, used to treat high blood pressure. Some other responsible drugs include epinephrine used for anaphylaxis and shock, the antipsychotic olanzapine and antidepressant duloxetine.
Type I Diabetes
Type I diabetes is caused by a disorder of the pancreas. The pancreas releases hormones that aid in digestion. One such important hormone is insulin. The pancreas releases insulin in response to a meal. Insulin causes cells to take up glucose from the blood for energy production, and signals the liver to store glucose as glycogen. In type I diabetes, the pancreas fails to release insulin. Without insulin, the cells cannot utilize glucose, and the levels rise in the blood.
Type II Diabetes
Type II diabetes is similar to type I diabetes in that the blood glucose levels rise, but the mechanism is different. In type II diabetes the pancreas works properly to release insulin into the bloodstream. In fact,the level of insulin may even be high. However, the cells are resistant to the effects of insulin. This type of diabetes is also called insulin-resistant diabetes.
Physiological Stress
Stress releases hormones such as cortisol and epinephrine from the adrenal gland into the blood. These hormones have many actions, including raising the blood glucose levels. Examples of significant stressors include surgery, stroke, heart attack and other forms of critical illness. High blood glucose during critical illness is an independent risk factor for slowed healing and complications.
References
- "Robbins and Cotran Pathologic Basis of Disease, Professional Edition"; Vinay Kumar et al; 8th Ed 2009
- "Harrison's Principles of Internal Medicine" Anthony S. Fauci et al; 17th Ed. 2008
