HbA1c

HbA1c (Glycated Hemoglobin)

HbA1c, also called glycated or glycosylated hemoglobin, forms when glucose in the blood attaches to hemoglobin in red blood cells. Red blood cells live for about 120 days, so HbA1c gives an overall picture of average blood sugar over the previous two to three months. That makes HbA1c far more informative than a single fasting glucose reading, which captures only one moment.

HbA1c is given as a percentage of total hemoglobin. In people without diabetes, HbA1c usually ranges from 4.0% to 5.6%. A value of 5.7-6.4% indicates prediabetes, and 6.5% or higher diagnoses diabetes. For most adults with type 2 diabetes, guidelines recommend aiming for an HbA1c below 7.0%, though individual targets may differ depending on the person and their risk of hypoglycemia.

In the Phase 2 retatrutide trial in type 2 diabetes (NCT04867785, published in The Lancet), participants started with a mean HbA1c of about 8.3%. Retatrutide lowered HbA1c in a dose-dependent way. The highest dose groups saw average drops of about 2.0 percentage points, bringing the average well below the 7.0% target. Many participants reached HbA1c levels below 5.7%, the normal, non-diabetic range. These results showed retatrutide’s strong glucose-lowering effect, driven by its combined GIP, GLP-1 and glucagon receptor activity.