is the case, any blood sugar at any time of day, above 140 is a concern, and a fasting sugar, taken in the morning with nothing to eat since midnight, should always be less than 100.
Blood sugars are mainly controlled by a hormone called insulin, though, other hormones such as adrenalin, glucagon, cortisol and growth hormone are involved to various extents in the maintainance of normoglycemia. Abnormality in these hormones can lead to either high blood sugars (diabetes) or low blood sugars (hypoglycemia).
Abnormal blood sugars can be evaluated by using;
1) Fasting blood sugars
2) Standard glucola 75 grams for adults and 75-100grams for pregnant women
3) Heavy carbohydrate meals
Normal blood sugars are defined differently based on wheter it is fasting blood sugar or non fasting blood sugar. When a person with out diabetes fasts for 8 hours the blood sugar should be less than 100mg/dl. On the other hand if the person eats food especially high in carbohydrates or standard glucola, the blood sugars should be less than 140mg/dl at 2 hours after eating a meal or glucola. Three hours after eating a meal a normal person should have blood sugars less than 100mg/dl. In a healthy person an hour after eating a big meal, the blood sugars should not be greater than 180mg/dl.
In a non diabetic patient the normal fasting blood sugars are between 70-100mg/dl. Any blood sugar below 70mg/dl is defined as hypoglycemia. And any fasting blood sugar greater than 100mg/dl is defined as hyperglycemia. Fasting blood sugars between 100-125mg/dl are defined prediabetes. Fasting blood sugars greater than 126mg/dl is considered diabetes.
We can also measure the status of blood sugars in a non diabetic patient using Hemoglobin A1c. Normal hemoglobin A1c is 4.5-5.6%. HBA1c between 5.7-6.4% is considered prediabetes and greater than 6.5% is demeed diabetes.
In diabetic patients HBA1c is used to monitor the progress of the treament of the diabetes while in healthy patients it can be used to diagnose diabetes.