Prediabetes means you have blood glucose, or blood sugar, levels that are higher than normal but not high enough to be called diabetes. Glucose comes from the foods you eat. Too much glucose in your blood can damage your body over time. If you have prediabetes, you are more likely to develop type 2 diabetes, heart disease, and stroke.
Most people with prediabetes don't have any symptoms. Your doctor can test your blood to find out if your blood glucose levels are higher than normal. If you are 45 years old or older, your doctor may recommend that you be tested for prediabetes, especially if you are overweight.
Losing weight - at least 5 to 10 percent of your starting weight - can prevent or delay diabetes or even reverse prediabetes. That's 10 to 20 pounds for someone who weighs 200 pounds. You can lose weight by cutting down on the amount of calories and fat you eat and being physically active at least 30 minutes a day. Being physically active makes your body's insulin work better. Your doctor may also prescribe medicine to help control the amount of glucose in your blood.
NIH: National Institute of Diabetes and Digestive and Kidney Diseases