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What to Know About Blood Glucose Levels
Type 2 Diabetes
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What to Know About Blood Glucose Levels

An Overview of Ideal Target Levels

Updated September 03, 2019
Medically reviewed by Richard N. Fogoros, MD

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Blood glucose, or blood sugar, is produced from carbohydrates in the diet to supply the cells throughout the body with energy. Normally, the body regulates blood glucose levels so there's always enough to fuel cells but not so much that the bloodstream is overloaded with sugar, which could cause significant damage.

For people with diabetes, the balancing of blood glucose levels is thrown off due to problems with insulin, a hormone produced by the pancreas that helps keep blood glucose levels steady and stable. In type 1 diabetes, the pancreas does not produce insulin at all. In type 2 diabetes, it produces too little insulin and/or the body isn't able to use it properly. The same is true for gestational diabetes, a temporary form of the disease the develops during pregnancy.

How Insulin Works in the Body

Because blood sugar fluctuates throughout the day depending on when food was last eaten, what was eaten, physical exertion, and other factors, monitoring glucose levels is a key aspect of managing all types of diabetes—particularly for those who take insulin.

Ideal Blood Glucose Levels

The specific level of blood glucose that's considered ideal for an individual depends on their age, how long they've had diabetes, medications they take, and any other medical conditions they may have, among other factors.

What's more, various health organizations differ in what they consider to be ideal glucose levels. Ultimately, if you have diabetes and blood glucose monitoring is a part of your treatment strategy, your doctor will have the last word on what your target glucose levels at any given time during the day should be. Even so, there are some general parameters worth knowing about, according to the American Diabetes Association (ADA).

Why Glucose Monitoring Is Important for Diabetes

Fasting Blood Glucose

Everyone experiences a hormone surge called the "dawn phenomenon" each morning several hours before they wake up. For people with diabetes, this hormone surge results in higher-than-normal blood sugar levels because they don't have a normal insulin response to adjust for it.

The dawn phenomenon happens because during the night the body produces less insulin while at the same time the liver produces more glucose. The lack of insulin results in a blood sugar rise in the morning.

The goal fasting blood glucose range for people with diabetes is 70 mg/dL.

If your fasting blood glucose is higher or lower than ideal most mornings, it may help to eat dinner earlier and avoid carbohydrates late at night. Exercising in the evening also may help keep your morning blood sugar within range. If you're on a diabetes medication, your doctor may want to adjust the time you take it or switching to a different one also may help.

Preprandial (Pre-meal)

Preprandial blood glucose refers to the level of sugar in the bloodstream before eating. Determining your pre-meal blood glucose and—this is key—recording it in a journal or with an app, will allow you and your doctor to identify trends in how your blood sugar levels rise and fall over time, which is an indication of how well your diabetes treatment is working.

Target Preprandial Blood Glucose Levels
Adults (who are not pregnant) 80 to 130 mg/dL  
Pregnant women with gestational diabetes 95 mg/dl or less  
Pregnant women with pre-existing type 1 or type 2 diabetes 60 mg/dL to 99 mg/dL  

Postprandial (Post-meal)

Postprandial blood glucose refers to blood sugar levels within an hour or two after meals and snacks. As with preprandial blood glucose testing, it's important to record your level each time you take it. You also should write down everything you ate and how much. This provides further information about how your body responds to certain foods, which in turn will help you and your doctor fine-tune your diet and other aspects of your diabetes management plan.

Target Postprandial Blood Glucose Levels
Adults (who are not pregnant) Less than 180 mg/dL  
Women with gestational diabetes, 1 hour after eating 140 mg/dL or less  
Women with gestational diabetes, 2 hours after eating 120 mg/dL or less  
Pregnant women with pre-existing type 1 or type 2 diabetes 120 mg/dL to 129 mg/dL  

Before and After Exercise

Regular physical activity generally is a key part of managing diabetes, especially for people with type 2 diabetes for whom losing weight could make an enormous difference in overall health. For those with type 1 diabetes, exercise can help increase sensitivity to insulin and control blood sugar.

However, because physical activity uses energy, it depletes cells of glucose, drawing glucose from the bloodstream and potentially leading to hypoglycemia. It's important, then, to check your blood sugar levels before you exercise as well as immediately afterward. This way you'll know if you have enough glucose to fuel your workout and you'll know the degree to which you've depleted it while exercising.

Target glucose ranges vary from person to person, but in general, it's ideal for blood sugar levels to be between 126 mg/dL and 180 mg/dL before starting exercise. If you test your blood glucose and it's lower than 126 mg/dL, here are the steps to take depending on the exact reading you get:

Pre-exercise blood glucose What to do
90 mg/dL or less Eat 10 to 20 grams (g) of carbs (i.e. ) and wait until glucose levels exceed 90 mg/dL. An apple with peanut butter should do it
90 mg/dL to 124 mg/dL Eat 10 g of carbs (a protein bar with 10 g of carbohydrate, for example) and then start high-intensity aerobic or anaerobic exercise 
126 mg/dL to 180 mg/dL It''re doing anaerobic exercise, monitor your blood glucose 
Over 270 mg/dL Check your blood ketones with a urine test. If only slightly elevated (up to 1.4 mmol/L) it''t make it easy. Our free nutrition guide is here to help. Sign up and receive your free copy!

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