Impaired fasting glucose (IFG) is an early warning sign that your blood sugar is higher than normal but not high enough to be diagnosed as diabetes. This condition is often called prediabetes — and it’s more common than many people realize. In fact, around 80 percent of people with prediabetes don’t know they have it. A fasting glucose test can give you key information about your risk.

If you have impaired fasting glucose, you may fear that type 2 diabetes is unavoidable. But that’s not necessarily true. Impaired fasting glucose is the perfect opportunity to pay more attention to your blood sugar and lifestyle choices. With the right support and information, you can make positive changes for a healthier future.

What Is Fasting Glucose?

Glucose is the main type of sugar in your blood. It provides energy to the brain and muscles. Doctors can measure how much glucose is in your blood using a simple blood test. This helps them understand how your body handles sugar and helps uncover hidden signs of prediabetes and diabetes. A normal fasting blood glucose test is between 70 and 99 milligrams per deciliter (mg/dL).

Eating foods or drinks that contain sugar causes blood glucose to rise. If you test after a meal, your blood sugar will be higher until your body absorbs or uses the energy. In people who don’t have diabetes or prediabetes, a normal blood glucose level before eating is 125 mg/dL or less.

Because food raises blood sugar, a fasting test is usually done in the morning before eating or drinking anything other than water. This gives a clearer picture of how your body manages sugar without the influence of your last meal.

What Is Considered Impaired Fasting Glucose?

Impaired fasting glucose is the term doctors use when your blood sugar levels are high, even when you haven’t eaten for at least eight hours. The range for IFG is between 100 and 125 mg/dL. Your healthcare provider will use this number, along with the results of other tests, to determine if you have prediabetes.

Prediabetes is a stage between healthy blood sugar control and type 2 diabetes. It puts you at an increased risk of developing type 2 diabetes, but there’s still time to make a change.

In diabetes, fasting blood glucose is typically 126 mg/dL or higher. Since IFG is a major risk factor for diabetes, it’s a good reason to learn more about how blood sugar works in your body. Understanding how your body handles sugar can empower you with the knowledge to protect your long-term health.

Additional Tests To Measure Glucose Control

Other tests that can help diagnose prediabetes include random blood glucose (not fasting), an oral glucose tolerance test, and a hemoglobin A1c test. A random blood glucose test measures your blood sugar at any time of day, regardless of the last time you ate. Having a random blood glucose of about 200 mg/dL is a sign of diabetes. In prediabetes, this number may be above 125 and under 200 mg/dL.

An oral glucose tolerance test is especially helpful for diagnosing prediabetes. It’s also commonly done in pregnancy to screen for gestational diabetes. You’ll go to the doctor’s office and drink a sweetened beverage that has a specific amount of sugar in it. Your healthcare provider will check your blood glucose level before you have the drink and at various times over the next two hours. They’ll use your results to see how your body processes sugar in real time.

In prediabetes, your blood glucose will be between 140 and 199 mg/dL two hours after the sugary drink. Under 140 mg/dL is considered normal, and 200 mg/dL or higher is diabetes.

Hemoglobin A1c gives an average of your blood sugar control over the past few months. You don’t have to fast before this test. It’s a good way to monitor blood sugar trends over time. Your hemoglobin A1c is the percentage of hemoglobin molecules (part of your red blood cells) that have sugar attached to them. A healthy range is under 5.7 percent. In prediabetes, hemoglobin A1c ranges between 5.7 and 6.4 percent. Diabetes is 6.5 percent or higher.

Insulin’s Role in Blood Glucose Regulation

IFG is an important sign that it’s time to focus on your insulin sensitivity. Insulin is the hormone that regulates or balances blood sugar. It helps your body use extra sugar from the blood for immediate energy or to store for future use.

IFG can be a sign that your body doesn’t make enough insulin. However, most people who have IFG or prediabetes are considered “insulin resistant.” That means their body makes enough insulin but doesn’t use insulin well. As a result, their blood sugar stays on the high side, which can cause damaging effects and inflammation throughout the body.

The opposite of insulin resistance is insulin sensitivity. Good insulin sensitivity helps keep blood glucose numbers in the healthy range. Fortunately, there are lots of things you can do to help boost your body’s insulin sensitivity.

How Do You Fix Impaired Fasting Glucose?

Food is one of the biggest lifestyle factors that influence insulin and blood sugar control. Managing stress, getting enough exercise, and sleeping well and deeply also play important roles. In some cases, lifestyle changes are all that’s needed to fix IFG.

People with prediabetes can benefit from cutting back on certain foods and increasing others. High-sugar foods and beverages should be avoided, as they directly raise blood sugar. In addition, watch out for carbohydrates that don’t contain fiber. These are also broken down quickly into sugar.

Healthy swaps include choosing whole grains instead of refined grains and whole fruits rather than fruit juice to make sure you’re getting some fiber. Focusing on nonstarchy vegetables and lean protein will help give your body the nutrition it needs while balancing your blood sugar.

Examples of nonstarchy vegetables include:

• Asparagus
• Broccoli and cauliflower
• Celery
• Cucumbers
• Eggplant
• Green beans
• Leafy greens, like spinach, kale, and lettuce
• Peppers
• Zucchini

Eating protein helps you feel full and supports strong muscles and bones. Protein can help fill the space on your plate where higher-sugar and carbohydrate foods used to be. You can get protein from a variety of animal-based and vegetarian sources, such as:

• Chicken breast
• Eggs
• Fish, including canned tuna and sardines
• Lean ground beef and turkey
• Plain cottage cheese or Greek yogurt (opt for low or nonfat)
• Tofu, edamame, and soybeans

A registered dietitian nutritionist can help you plan healthier meals. Also, if you have excess weight, weight loss can help prevent or delay type 2 diabetes. Don’t be afraid to ask your healthcare provider for support and resources to improve your health.

However, if lifestyle changes aren’t making enough of a difference in your blood test results, you may need medication to keep your fasting glucose in the healthy range. Medication (like metformin) is available to increase insulin sensitivity and improve blood sugar control. Your healthcare provider can give you advice on your best options.

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