Understanding HbA1c (Glycated Hemoglobin): What It Means & How to Read It

What is HbA1c (Glycated Hemoglobin)?

The HbA1c test measures the percentage of hemoglobin molecules within red blood cells that are chemically bonded to glucose. Because erythrocytes have an average lifespan of approximately 120 days, HbA1c acts as a biological ledger reflecting average glycemic exposure over the preceding 2 to 3 months.

Diagnostic Criteria - **Normal (Non-diabetic):** Below 5.7% - **Prediabetes:** 5.7% to 6.4% - **Diabetes:** 6.5% or higher on two separate confirmatory occasions

Clinical Targets for Diabetes Management For most non-pregnant adults, the clinical target is typically **< 7.0%**. Landmark clinical trials demonstrate that each 1% absolute reduction in HbA1c is associated with an over 35% reduction in microvascular complications (retinopathy, nephropathy, and neuropathy).

Why HbA1c Does Not Replace Daily Fingerstick Logs HbA1c represents an average; it fails to illustrate glycemic variability, acute postprandial spikes, or asymptomatic nocturnal hypoglycemic events. Pairing daily SMBG with quarterly HbA1c assessments provides comprehensive clinical intelligence.

Scientific References & Evidence Sources:

• The Diabetes Control and Complications Trial (DCCT) Research Group
• UK Prospective Diabetes Study (UKPDS)