HbA1c refers to glycated hemoglobin. Hemoglobin, which carries oxygen, joins with glucose in the blood, becoming "glycated". As RBCs in the human body survive for 8-12 weeks before renewal, measurement of HbA1c can be used to reflect average blood glucose levels over that duration. This method provides a useful longer-term gauge of blood glucose control. The value of HbA1c is less than 6% in normal individuals whereas in prediabetes, it is 6.0-6.4% and in diabetics, it is above 6.5%. Higher the HbA1c, the greater the risk of developing diabetes-related complications.