The glycemic index is a measure of the effect that foods containing carbohydrates have on your blood sugar levels. The effect that these foods have on your blood sugar is compared to glucose, the reference food, which has a glycemic index score of 100. Although high in fat, butter will not impact your blood sugar.
Butter and Blood Sugar
Butter is not included in the glycemic index because it does not contain carbohydrates. Foods that do not have carbohydrates do not directly affect blood sugar in the same way that foods with carbohydrates do, and they are not included in the glycemic index. Just remember that you should limit your consumption of butter due to its saturated fat content.