If someone with type 2 diabetes has red blood cells that don’t live as long, their A1c test might be giving a lower number than their real blood sugar levels — meaning the test could be misleading for them.

If someone with type 2 diabetes has red blood cells that don't live as long as usual, their A1c test might show better blood sugar control than they actually have — meaning doctors could miss signs of high blood sugar over time.

Some people with diabetes might seem to have good blood sugar control based on standard tests, but if their red blood cells don’t live as long, the test could be misleading — and nearly 1 in 3 of these patients might actually have worse blood sugar levels than the test shows.

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.

If someone with type 2 diabetes has good HbA1c numbers but their red blood cells don’t live as long, their blood sugar might actually be higher than the test shows — meaning the test could be giving them a too-rosy picture of their sugar control.

Even when blood sugar averages look good on a diabetes test, people with shorter-lived red blood cells might still have higher actual sugar levels throughout the day.