Diagnostic tests for diabetes details about Fasting glucose level glucose tolerance test and Hemoglobin A1C test and their relevance.
In order to diagnose if a person is pre diabetes, or a diabetic his blood sugar level is measured, along with various other diagnostic tests for diabetes
Fasting blood sugar level diagnostic tests for diabetes.
Blood glucose level is measured after overnight fasting, sugar level 99 mg/DL is considered normal, reading of 100 to 125 mg/DL is considered prediabetes.
Blood sugar level above 126 mg/DL is considered diabetic, also a random sample showing blood glucose level above 200 is considered diabetic.
Glucose tolerance test diagnostic test for diabetes :
A patient is asked to remain fasting overnight, a blood sample is drawn and blood glucose level is measured. After which the patient is given a drink containing sugar and diet. After the drink and diet patients blood sugar is measured.
Blood sugar level of 200 mg/DL is considered diabetic.
Glycated hemoglobin, HbA1C Glucose conjugated with hemoglobin:
As the blood glucose level in the blood increases due to the nature of the glucose and fructose they bind with the Nitrogen Terminal (N-Terminal amino acid of the hemoglobin) and form a conjugate of hemoglobin and glucose, it’s not only the glucose but other sugar molecules like fructose and galactose too bind with the hemoglobin. hemoglobin complexed with a glucose molecule is called HbA1C.
More is the blood glucose level more is the amount of HbA1C glucose bonded with hemoglobin.
Why HbA1C is a measure of blood glucose level for three months.
The HbAc1 is the glucose bound to hemoglobin, hemoglobin once bound with the glucose molecule stays as such for the life span of the red blood cell. Red blood cell life span is about 4 months therefore it is said that HbA1C gives the value of blood sugar over the past three months. HbA1c is measured in amount of glucose molecule bound to one molecule of hemoglobin, number or millimoles/mole, and its expressed in the percentage of hemoglobin molecule occupied by blood sugar.
Limit of HbA1c:
HbA1c below 6.5 % is normal
HbA1c 6.5 % is considered as prediabetes.
HbA1c more than 6.5 % is diabetic.
Harmful effects of hemoglobin bonded with glucose:
Patients affected with diabetes, have higher levels of glucose in their blood, the glucose binds with hemoglobin and saturates hemoglobin. This activates the iron ion in the hemoglobin that starts damaging blood vessels. Precipitates diseases like atherosclerosis and autoimmune disease.
The higher concentration of glucose bound hemoglobin is sensed as foreign antigen by immune system and our body starts to produce the antibodies against our own body cells of the blood capillaries, and blood vessels, liver, the organs which are involved in storage of hemoglobin and iron and metabolism of iron.