The normal fasting blood sugar range for adults aged 40 to 50 is generally the same as for other non-pregnant adults. A fasting blood sugar level of 70 to 99 mg/dL is considered normal, while 100 to 125 mg/dL indicates prediabetes and 126 mg/dL or higher may suggest diabetes. A normal blood sugar level two hours after a meal is generally below 140 mg/dL. Your doctor may recommend different target levels if you already have diabetes.