In pregnant women who don’t have diabetes, having denser hemoglobin in their red blood cells might be linked to slightly higher blood sugar levels over time.

In pregnant women who don’t have diabetes, blood traits like hemoglobin and hematocrit can slightly predict their average blood sugar levels — but other traits like MCHC and PDW don’t hold up when we adjust for other factors.

In pregnant women without diabetes, having more hemoglobin in the blood is linked to slightly higher HbA1c levels — a marker usually tied to blood sugar — suggesting that blood cell levels might affect this test even if sugar isn't high.

In pregnant women without diabetes, having more red blood cells might make their blood sugar test results look higher than they really are, even if their actual sugar levels are normal.

In pregnant women who don’t have diabetes, things like red blood cell size and volume don’t seem to affect their HbA1c blood test results in any meaningful way.

In people with type 2 diabetes, red blood cells don’t live as long when there’s a bigger mismatch between their actual HbA1c levels and what those levels should be based on blood sugar — meaning the body’s sugar coating on blood cells doesn’t always match up with sugar levels.