Overview of Glucose Challenge Test
What is Glucose Challenge Test?
Preparation for Glucose Challenge Test
- No special preparation required
Why Get Tested for Glucose Challenge Test?
The Glucose Challenge Test is performed to:
· Screen for high blood sugar in presence of risk factors for diabetes in pregnancy
· Detect gestational diabetes
Understand more about Glucose Challenge Test
Glucose is a simple sugar or monosaccharide which is the main source of energy for all the cells of the body, and the only energy source for the nervous system. Carbohydrates consumed in the diet are broken down in the body to their simplest form: glucose, which is absorbed by the intestines and transported by the blood to various organs. Glucose is subsequently utilized by cells of these organs to produce energy wherever necessary, and the excess is stored either as glycogen in the liver for short term storage or in fat tissues as triglycerides for long term storage. The uptake, utilization, and storage of glucose after it is absorbed in the intestines are facilitated by the hormone- insulin secreted by the pancreas. Insulin influences the transport of glucose to the organs requiring it, like the heart, brain, working muscles, etc. It also directs storage of excess glucose. The action of insulin reduces sugar levels in the blood.
After a meal, sugar levels increase in blood and insulin is secreted in response to reduce sugar levels until it becomes normal. If glucose levels fall too low in blood, another pancreatic hormone called glucagon is released, which directs the liver to convert stored glycogen into glucose and release it into the blood. The insulin and glucagon hormones create a feedback mechanism to keep blood glucose levels within the normal range. Imbalance in their activity causes an excess or shortage of blood sugar.
The glucose challenge test measures the levels of glucose in the blood, one hour after the administration of a sugar solution (usually 50 gm glucose dissolved in about 300 ml water). This helps to determine if the body is able to utilize or store glucose efficiently. Excess sugar in blood indicates it is not being utilized or stored. It is usually performed as a part of the panel of tests performed during pregnancy and can be performed at any time during pregnancy. It is also necessary to repeat the test at 24 to 28 weeks to detect gestational diabetes.
What Results of Glucose Challenge Test mean?
Normal range: Less than 130 to 140 mg/dL (7.2 to 7.8 mmol/L)
A cut-off value of 140 mg/dL (7.8 mmol/L) identifies 80% of women with Gestational diabetes.
A cut-off value of 130 mg/dl (7.2 mmol/L) identifies 90% of women with Gestational diabetes.
Blood sugar levels higher than the normal range indicates increased blood sugar due to the inability of the body to process it.
GCT is a screening test for Gestational diabetes and continuously raised blood sugar levels in subsequent tests indicate a strong possibility of gestational diabetes. Further tests like 2-hour or 3-hour Glucose Tolerance Tests (GTT) are performed to diagnose Gestational diabetes.
Patient Concerns about Glucose Challenge Test
Frequently Asked Questions about Glucose Challenge Test