A normal blood glucose reading does not necessarily rule out prediabetes, as HbA1c offers a longer-term view of blood sugar trends. Experts emphasise using both tests for accurate diagnosis.
A blood glucose reading of 81 mg/dL and an HbA1c result of 5.7% can both be accurate, because they measure different things. Dr Vijay Negalur, head of diabetology at KIMS Hospitals in Thane, told The Indian Express that a spot glucose test shows blood sugar at one moment, while HbA1c reflects the average level over roughly the previous two to three months. That means a normal reading on one test does not rule out a borderline result on the other.
Medical guidance from MedlinePlus and the US National Institute of Diabetes and Digestive and Kidney Diseases says HbA1c works by measuring how much glucose has attached to haemoglobin in red blood cells, which carry glucose exposure over the life of those cells. By contrast, a single glucose test can shift quickly with meals, exercise, stress, sleep and other day-to-day factors. In practical terms, the first is a snapshot; the second is a longer-term trend.
That is why doctors often use both tests together when checking for prediabetes or diabetes. A normal finger-prick or laboratory glucose level may look reassuring, but it cannot capture patterns of repeated higher readings. An HbA1c of 5.7% sits at the lower edge of the prediabetes range, so the result is usually a prompt to look more closely at overall lifestyle, eating habits and repeat testing rather than to rely on one number alone.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
