Glucose intolerance is also known as prediabetes, a condition in which blood glucose levels are higher than normal but not high enough for a diagnosis of diabetes. Symptoms of prediabetes include increased thirst, frequent urination, dark patches of skin, blurred vision and fatigue. Prediabetes is a risk factor for full-blown diabetes and metabolic syndrome, an imbalance in blood sugar, cholesterol and blood pressure.
Glucose and Insulin
In healthy individuals, the pancreas responds to glucose that enters the bloodstream from the digestive system by producing insulin, a hormone that helps inform the cells when glucose is available in the bloodstream. Insulin binds to cell receptors on the cells' surfaces. This causes glucose transporters to embed into the cell membranes and transport glucose into the cells. The cells can then use it as immediate energy or store it in the form of glycogen or fat.
Insulin Resistance
Insulin resistance is a condition in which the insulin receptors on cells surfaces have become resistant to insulin. When this happens, insulin cannot transfer its signal to the interior of the cells as well as in healthy individuals. So, the uptake of glucose from the bloodstream is delayed. This gives rise to elevated blood glucose levels, even after an 8-hour overnight fast. Insulin resistance is the most common form of prediabetes. It can lead to type-2 diabetes if it goes untreated. Type 2 diabetes is a severe case of insulin resistance in which little information passes from insulin receptors to the cells' interior. This can lead to an accumulation of blood sugar and plaque formation in the blood vessels.
Metabolic Syndrome
Metabolic syndrome is a range of conditions that may or may not have a common cause. According to the American Heart Association, metabolic syndrome is associated with high blood pressure, high levels of bad cholesterol and free triglycerides, low levels of good cholesterol and insulin resistance. Metabolic syndrome is significantly correlated with glucose intolerance, but a wide range of underlying conditions are risk factors for metabolic syndrome, including abdominal obesity, physical inactivity, hormonal imbalance and aging.
Treatment
A common way to treat metabolic syndrome is to control the elevated blood glucose levels. Doctors normally prescribe blood glucose medications in combination with a low-carb diet or a glycemic-index diet for blood sugar control. A low-carb diet, such as the Atkins diet, restricts all carbohydrates, the main source of glucose, to between 20 and 100 g. This can contribute to low, steady blood glucose levels. A glycemic diet restricts high-glycemic carbohydrate foods, such as sweets, breaded foods, white bread and white pasta, but allows low-glycemic carbohydrate foods, such as whole grain products, vegetables, fruits and legumes. As low-glycemic carbohydrate foods are high in fiber, and a diet high in fiber can lower blood sugar levels, a glycemic index diet can also have a stabilizing effect on blood glucose.
References
- "Circulation"; Diagnosis and Management of the Metabolic Syndrome; Scott M. Grundy, et al.; September 2005
- National Diabetes Information Clearinghouse: Insulin Resistance and Prediabetes
- Science Daily: Low Glycemic Index Diet Best For Weight Loss And Cardiovascular Health
- American Diabetes Association: Glycemic Index and Diabetes
- City of Hope; Sugar's Bitter Toll on Blood Vessels; Darrin S. Joy; June 2010
- Mayo Clinic: Glycemic Index Diet: Losing Weight With Blood Sugar Control
