Pre‑Diabetes: Understanding Your Blood Work — A1c vs. Glucose

Many people learn they have pre‑diabetes from a simple blood test. Two common tests are the A1c test and the fasting glucose test. These tests both look at blood sugar, but they measure different things. Knowing the difference can help you understand what is happening in your body.

What Is the A1c Test?

The A1c test shows your average blood sugar over the last three months. Your red blood cells carry sugar on them, and the A1c test measures how much sugar is stuck there.

• It does not change from one meal.

• It shows long‑term patterns.

• A higher A1c means your blood sugar has been high for many weeks.

What Is the Fasting Glucose Test?

The fasting glucose test measures your blood sugar at one moment in time. You take this test after not eating for 8–12 hours.

• It can change based on stress, sleep, or illness.

• It can rise after eating a lot of sugar or refined carbs the night before.

• It helps show short‑term changes in blood sugar.

How Nutrition Affects These Tests

Food plays a big role in both tests.

Fasting Glucose:

• High‑sugar or high‑carb meals can raise your number the next morning 

• Not eating enough protein or fiber can cause quick spikes

A1c: 

• Eating lots of sugary foods over time can raise your A1c 

• A diet low in fiber and high in processed foods can keep blood sugar high 

• Balanced meals help keep blood sugar steady over weeks and months

Three Actionable Steps to Support Healthy Blood Sugar

1. Build Balanced Meals

   Include protein (like eggs, chicken, tofu), fiber (like veggies, beans, whole grains), and healthy fats (like nuts or avocado) at each meal.

   
   

2. Choose Fiber‑Rich Carbs

   Pick whole fruits, vegetables, beans, and whole grains more often than refined carbs like white bread, pastries, or sugary drinks.

   
   

3. Eat Consistently

   Try not to skip meals. Eating regularly helps keep your blood sugar steady throughout the day.

References

American Diabetes Association. “Understanding A1c.”

Centers for Disease Control and Prevention (CDC). “Prediabetes: Your Chance to Prevent Type 2 Diabetes.”

National Institutes of Health. “Blood Glucose Tests.”

Harvard School of Public Health. “Carbohydrates and Blood Sugar.”