From the DoIHavePreDiabetes.org website:

One in three American adults has prediabetes, but only 10 percent of them know they have it. Prediabetes means a person's blood glucose (sugar) level is higher than normal, but not high enough yet to be diagnosed with diabetes. People with prediabetes are on the road to develop type 2 diabetes within several years, and are also at increased risk for serious health problems, such as stroke and heart disease. There are some prediabetes risks you can't control, like age and family history. But there are things you can do to reduce your risk, such as increased physical activity and weight loss. And making these lifestyle changes can also help prevent or delay the onset of type 2 diabetes.

There are not usually symptoms when you have prediabetes. Talk to your doctor to know for sure. A simple blood test can confirm if you have prediabetes.