Can You Have Diabetes with Normal HbA1c Levels?

It may come as a surprise, but yes — it is entirely possible to have diabetes even when your HbA1c (glycated hemoglobin) levels appear normal. While HbA1c is widely used as a reliable marker for long-term blood glucose control, reflecting average blood sugar levels over the past 2 to 3 months, it's not infallible. Certain medical conditions and physiological variations can skew results, leading to potential misdiagnoses or delayed detection of diabetes.

Understanding HbA1c and Its Limitations

HbA1c, also known as glycosylated hemoglobin, forms when glucose in the bloodstream attaches to hemoglobin in red blood cells. The higher the blood glucose levels over time, the more glycated hemoglobin is produced. This makes HbA1c a valuable tool in diagnosing and monitoring diabetes. However, its accuracy depends heavily on the lifespan and integrity of red blood cells.

Medical Conditions That Affect HbA1c Readings

Anemia is one major factor that can distort HbA1c results. In individuals with iron deficiency or other forms of anemia, red blood cell production is impaired, leading to lower hemoglobin levels. With fewer red blood cells available for glucose attachment, the resulting HbA1c value may appear falsely normal — even if blood glucose levels are frequently elevated.

Similarly, patients with chronic kidney disease (CKD) may experience reduced erythropoietin production, a hormone responsible for stimulating red blood cell formation. This condition shortens red blood cell lifespan and alters glycation dynamics, potentially masking high blood sugar levels. As a result, someone with undiagnosed type 2 diabetes could show a deceptively normal HbA1c reading.

Fluctuating Blood Glucose: The Hidden Risk

Another scenario involves individuals with highly variable blood glucose levels — experiencing both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) throughout the day. Because HbA1c reflects an average, these extreme fluctuations might cancel each other out, producing a result within the "normal" range despite poor overall glucose control.

This pattern is particularly common in people with type 1 diabetes or those developing insulin resistance, where glucose instability often precedes a formal diagnosis. Relying solely on HbA1c in such cases increases the risk of missing early signs of diabetes.

The Importance of Comprehensive Testing

Given these limitations, healthcare providers should consider additional diagnostic tools when diabetes is suspected — especially in high-risk populations. The 75g oral glucose tolerance test (OGTT) remains a gold standard for detecting impaired glucose metabolism. Unlike HbA1c, this test measures how efficiently the body processes glucose after a controlled sugar intake, offering real-time insight into insulin function.

Fasting plasma glucose tests and continuous glucose monitoring (CGM) systems are also valuable alternatives, particularly for individuals with conditions affecting red blood cell turnover.

Key Takeaway: Don't Rely on HbA1c Alone

Normal HbA1c does not always rule out diabetes. Symptoms like excessive thirst, frequent urination, unexplained fatigue, or blurred vision should never be ignored — even with acceptable lab results. A holistic approach that includes clinical evaluation, symptom assessment, and multiple testing methods ensures earlier detection and better long-term outcomes.

If you're at risk for diabetes due to family history, obesity, or other metabolic conditions, talk to your doctor about comprehensive screening options beyond HbA1c testing alone.