Hemoglobin is a protein found only in red blood cells that carries oxygen from your lungs to the body's tissues and returns carbon dioxide from the tissues back to the lungs. When sugar enters the bloodstream, it attaches and sticks to hemoglobin molecules to form Hemoglobin A1c. The hemoglobin A1c test is an important tool used by healthcare professionals for the screening, diagnosis, and management of prediabetes and diabetes. This blood test measures your average blood sugar levels over the past 3 months.

Blood glucose is the main sugar found in your bloodstream. The sugar comes from the food you eat and supplies energy to all cells in the body. However, it needs to stay within safe levels to reduce the risk of diabetes and associated disorders, such as heart disease. Your body also needs insulin to keep blood sugar levels normal. Insulin is a hormone produced by the pancreas that helps store glucose in the liver, muscles, and fat; controls the amount of glucose in your blood; and regulates how your body uses carbohydrates, fats, and proteins. When you don't have enough insulin or it isn't working properly, the body cannot effectively process blood sugar, resulting in high blood sugar levels and, ultimately, diabetes. If high blood sugar levels are left untreated, you may develop a chronic health condition that may lead to damage to many bodily systems, including blindness, limb amputation, heart disease, heart attack (myocardial infarction), stroke, kidney failure, nerve damage, skin disorders, and an increased risk for limb amputation.