Prediabetes is a warning phase that blood sugar is higher than it should be, but not so high that it causes a diabetes diagnosis. Diabetes is a disease where the body loses its ability to manage sugar levels because the body is not able to move sugar from the blood into muscles and other organs. Type 1 diabetes is an autoimmune condition where the body attacks the pancreas, the organ that makes insulin which supporting the movement of sugar out of blood.

Prediabetes Risk Factors

You are at risk for prediabetes if any of the following are true:

• You are overweight or obese.
• You have a parent, brother, or sister who has diabetes.
• You had diabetes during pregnancy (called gestational diabetes) or had a baby who weighed more than 9 pounds at birth.
• You are African American, Native American, Latin American or Asian/Pacific Islander.
• You have high blood pressure (above 140/90 mm Hg).
• Your HDL cholesterol level (“good” cholesterol) is too low (less than 40 mg per dL for men or 50 mg per dL for women), or your triglyceride level is higher than 250 mg per dL.
• You are a woman who has polycystic ovary syndrome (PCOS).

If you have one or more of these risk factors, you can easily modify them by following some of these actionable tips. 

Prediabetes Diagnosis

There are several blood tests for prediabetes.

Glycated hemoglobin (A1C) test

This test indicates your average blood sugar level for the past two to three months. Specifically, the test measures the percentage of blood sugar attached to the oxygen-carrying protein in red blood cells (hemoglobin). The higher your blood sugar levels, the more hemoglobin you'll have with sugar attached.

General Guideline:

• An A1C level below 5.7 percent is considered normal
• An A1C level between 5.7 and 6.4 percent is considered prediabetes
• An A1C level of 6.5 percent or higher on two separate tests indicates type 2 diabetes
• Certain conditions can make the A1C test inaccurate — such as if you are pregnant or have an uncommon form of hemoglobin (hemoglobin variant).

Fasting blood sugar test

A blood sample is taken after you fast for at least eight hours or overnight.

General Guideline:

• A fasting blood sugar level below 100 milligrams per deciliter (mg/dL) — 5.6 millimoles per liter (mmol/L) — is considered normal.
• A fasting blood sugar level from 100 to 125 mg/dL (5.6 to 7.0 mmol/L) is considered prediabetes. This result is sometimes called impaired fasting glucose.
• A fasting blood sugar level of 126 mg/dL (7.0 mmol/L) or higher indicates type 2 diabetes.

Oral glucose tolerance test

This test is usually used to diagnose diabetes only during pregnancy. A blood sample is taken after you fast for at least eight hours or overnight. Then you'll drink a sugary solution, and your blood sugar level will be measured again after two hours.

General Guideline:

• A blood sugar level less than 140 mg/dL (7.8 mmol/L) is considered normal.
• A blood sugar level from 140 to 199 mg/dL (7.8 to 11.0 mmol/L) is considered prediabetes. This is sometimes referred to as impaired glucose tolerance.
• A blood sugar level of 200 mg/dL (11.1 mmol/L) or higher indicates type 2 diabetes.

If you have prediabetes, further testing may be needed. At least once a year, your doctor will likely check your:

• Fasting blood sugar
• Hemoglobin A1C
• Total cholesterol, HDL, low-density lipoprotein (LDL), and triglycerides

Testing might occur more frequently if you have additional risk factors for diabetes.

Prediabetes and complications

It is important to be aware that high blood sugar in prediabetes can cause diabetes complications. The most common complication is nerve damage what affects 1 in 4 with prediabetes. There are specific strategies that you can use that decrease the risk of developing complications. 

Children and prediabetes testing

Type 2 diabetes is becoming more common in children and adolescents, likely due to the rise in childhood obesity. The ADA recommends prediabetes testing for children who are overweight or obese and who have at least two other risk factors for type 2 diabetes.