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A1C Assay

A1C assay and estimated average plasma glucose (eAG)#

An A1C assay suggests a median plasma glucose level for the past three months. Patients with A1C levels above 9% need improved glycemic control and are at an increased risk of infection, poor wound healing, oral candidiasis, oral burning sensations, and aggressive periodontal disease.

A1c and plasma glucose#

  • HbA1c – measures metabolic control over 2-3 months period; may suggest long-term adverse effects on the body’s ability to fight infections.
  • Plasma glucose – measures present metabolic control; may suggest immediate adverse events due as hypo- or hyperglycemia.
  • Normal adult range - A1c = <5.4%
  • High risk/pre-diabetes - A1c = 5.4% - 6.4%
  • Diabetes, confirmed by repeating the test on a different day - A1c = ≥6.5%
  • 28.7 x A1C – 46.7 = eAG (mg/dL)

An estimated Average Glucose (eAG) calculator is available.

Charcateristics of A1c tests#

  • Assay is well standardized
  • Does not require fasting blood
  • Not affected by day-to-day lifestyle changes
  • Tightly correlated with risk of developing retinopathy
  • Effect modifiers: uncommonly high doses of salicylates, vitamins C, E and SEVERE iron deficiency
  • Easy, rapid, safe, validated
  • Similar sensitivity (63%) and superior specificity compared to random plasma glucose (97% vs 87%)

Related Pages#