Healthy number: A fasting blood-sugar level of 99 mg/dL or less.
A fasting blood-sugar test measures glucose (sugar) in milligrams per deciliter (mg/dL) of blood after you haven’t eaten for at least eight hours. A level of 126 mg/dL or higher indicates diabetes, a condition in which your body doesn’t produce enough insulin (which converts blood sugar into energy) or use insulin properly. Diabetes more than doubles your risk of heart disease and increases your chances of kidney disease, vision loss, and other health issues.
Have yours checked: At age 45, then every three years after that. (Your doctor may test you earlier if you are overweight or have a family history of diabetes.) Some doctors also do a hemoglobin A1C test, which measures glycated hemoglobin (HbA1C), a substance in red blood cells that forms when glucose attaches to hemoglobin. This “gives a better picture of average blood sugar over the previous three months,” says Wendy S. Klein, an internist in Richmond, Virginia. An optimal A1C reading is less than 5.7 percent. To improve your blood-sugar numbers, shed any excess pounds.