What is Diabetes Screening?
Diabetes screening test includes two sets of test: Glycosylated Hemoglobin test and Glucose - Fasting blood test. Generally, this test is advised to those patients who are at risk of diabetes. However, this test is highly recommended for people who are obese and have a previous history of diabetes or heart disease in their family. In addition, this test is used to monitor blood glucose levels in diabetic patients.
Why is Diabetes Screening done?
To screen for high blood sugar in presence of risk factors of diabetes
To screen for diabetes as a part of routine health checkup
To monitor blood glucose levels in diabetic patients
To detect diabetes during pregnancy or gestational diabetes
To monitor treatment efficacy in patients undergoing treatment for diabetes
What does Diabetes Screening Measure?
Diabetic screening includes two set of tests - Glycosylated Hemoglobin test and Glucose - Fasting blood test.
Glycosylated Hemoglobin Test measures the percentage of glycosylated hemoglobin in blood which reflects the average blood glucose over a period of past two to three months (8 - 12 weeks).
Hemoglobin is a protein found in Red Blood Cells and is responsible for transporting oxygen. There are different types of hemoglobin among which Hemoglobin A is predominant. With the elevation of blood sugar levels, some glucose binds spontaneously to Hemoglobin A (this binding is called Glycosylation or Glycation) and remains bound for the complete lifetime of the RBC, which is normally 120 days. Higher the level of glucose in the blood, the greater the amount of it binding to Hemoglobin A. Hemoglobin A1c is the dominant form of Glycated Hemoglobin. As RBCs die and get replaced, Hemoglobin A1c is cleared and gets slowly replaced with non-glycosylated hemoglobin. Measurement of HbA1c level over a period of time gives an indication of the level of glucose in the blood over that specific period of time. This not only helps in the diagnosis of Diabetes but also is useful for monitoring the effectiveness of measures taken to reduce blood sugar levels.
Glucose - Fasting Blood Test is done to measure the levels of glucose in blood during the period of fasting.
Glucose is the main source of energy for the body. Carbohydrates consumed in the diet are broken down in the body to form glucose, which is absorbed by the intestines and transported by the blood to various organs. The cells of these organs utilize the glucose to produce energy when required, 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 has been absorbed in the intestine is facilitated by a hormone called insulin. This hormone is secreted by the pancreas. Insulin influences the transport of glucose to the organs like heart, brain, working muscles, etc. It also directs the storage of excess glucose. These actions of insulin reduces sugar levels in the blood.
After a meal, sugar levels increase in blood, and insulin is secreted in response to reduce the sudden increase in sugar levels until it becomes normal. If in this process glucose levels fall too low in blood, another pancreatic hormone called glucagon is released. This hormone, directs the liver to convert stored glycogen into glucose and releases it into the blood. Both these hormones, insulin and glucagon, create a feedback mechanism to keep blood glucose levels within the normal range. Any imbalance in their activity causes an excess or shortage of blood sugar.
Glucose - Fasting blood Test helps to determine if the body is able to utilize or store glucose efficiently. High levels of sugar in blood indicate diabetes or resistance to insulin. Type 1 Diabetes is caused when insulin is not produced or produced in very little quantity. Type 2 Diabetes is caused when insulin is produced but is not being effectively utilized by the body. In both these cases, blood sugar levels rise, while cells remain deprived of nutrition.
Interpreting Diabetes Screening results
Normal: Below 5.7% (39 mmol/mol approx.)
Prediabetic: 5.7% - 6.4% (39 to 46 mmol/mol approx.)
Diabetic: Above 6.5% (above 48 mmol/mol approx.)
Less than 5.7% Glycated Hemoglobin indicates normal levels of blood sugar. Increased risk of developing Diabetes is found in Prediabetic patients with blood sugar level between 5.7% and 6.4%. Patients with HbA1c level greater than 6.5% are usually diagnosed with Diabetes.
Glucose - Fasting Blood:
Normal fasting glucose range: 70 to 99 mg/dL (3.9 to 5.5mmol/L)
Prediabetes: 99 to 126 mg/dL (5.5 mmol/L to 7.0 mmol/L)
Diabetes: Higher than 126 mg/dL (7.0 mmol/L) in multiple subsequent tests
Tests Included (2 tests)
- Glycosylated Hemoglobin