A high blood sugar reading does not always mean a person has diabetes; he or she may have a condition known as prediabetes. Prediabetes puts a person at a much higher risk of developing diabetes. Other causes of high blood sugar include eating a carbohydrate-rich meal or experiencing stress.
Prediabetes not only puts a person at a higher risk of developing diabetes, but also puts him or her at a higher risk for stroke and heart disease, according to the National Institutes of Health. Often, implementing a healthier eating plan along with exercise can prevent type 2 diabetes, even with a diagnosis of prediabetes.
Early on, prediabetes and diabetes may show no symptoms and the only way of diagnosing these diseases is through blood tests such as a fasting plasma glucose test or an oral glucose tolerance test.