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Article by Lahle Wolfe, Founder, Islets of Hope.  For article use and reprint permission please contact:

American Diabetes Association
Diabetes Health Net
EMedicine - Fred Smeeks, MD
EDoctor UK
Nat'l Diabete Info Clearinghouse
UVA Health

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Normal Blood Glucose

Information on normal and acceptable target blood glucose ranges for both diabetics and nondiabetics. Our chart considers factors such as age and whether or not a person is newly diagnosed.

(Low Blood Sugar)


(High Blood Sugar)


Hypoglycemia in Non-Diabetic Persons
Reactive Hypoglycemia
Fasting Hypoglycemia
Other Causes for Hypoglycemia

Two types of hypoglycemia can occur in people who do not have diabetes: reactive (postprandial, or after meals) and fasting (postabsorptive). Reactive hypoglycemia is not usually related to any underlying disease; fasting hypoglycemia often is.

(LOW Blood Glucose)

Onset:  Rapid; sudden, may not be preventable.

Causes Related to Diabetes: Missing snacks or meals, eating too little food, taking too much insulin, too much activity, side effects of medications taken, or a combination of these things.

ALERT:  All lows are potentially dangerous and can lead to seizure, convulsion, unconsciousness, and death if not treated.  If you are unable to test someone's blood glucose, always assume the person is low and treat for low blood glucose.  Call 911 and test blood glucose as soon as possible.


Mild Hypoglycemia
Increased or sudden hunger
Feeling shaky, dizzy or nervous
Pounding heartbeat
Drowsiness, feeling tired
Sweating (cold and clammy)
Numbness/tingling around mouth
Headache or stomachache

Moderate Hypoglycemia
Any mild symptoms above, plus:
Personality change
Confusion and/or difficulty      concentrating
Slurred or slow speech
Poor coordination

Severe Hypoglycemia
***CALL 911 ASAP!***

Any of the above symptoms plus:
Loss of consciousness
Seizures and/or convulsions

Severe hypoglycemia requires injection of glucagon!

What to Ask Your Doctor About Your Diabetes Medications

  • Could my diabetes medication cause hypoglycemia?

  • When should I take my diabetes medication?

  • How much should I take?

  • Should I keep taking my diabetes medication if I am sick?

  • Should I adjust my medication before exercise?

Did You Know?

... that exercise can cause hypoglycemia? Check your blood glucose before you exercise and afterwards.  If you are active for a long time, or, feel any of the symptoms of abnormal blood glucose levels (high or low) check during exercise as well.


islets of hope diabetes medical library            back to main "Glycemia Information"
Diabetes Information                                                                        
Printable Version of this Article

Causes of diabetic hypoglycemia
(also called low blood glucose or low blood sugar)

Mini Site Index
About Hypoglycemia
Common Causes of Low Blood Glucose
Side Effect of Certain Medications
Insulin Pumps & Hypoglycemia
Bathing, Hot Tubs, and Saunas & Hypoglycemia
Normal Blood Glucose Ranges
Normal and Target Blood Glucose Ranges in mg/dL for Diabetics
More Information 

About Hypoglycemia

Hypoglycemia, also called low blood sugar or low blood glucose, occurs when your blood glucose (sugar) level drops too low to provide enough energy for your body's activities. In adults or children older than 10 years, hypoglycemia is uncommon except as a side effect of diabetes treatment, but it can result from other medications or diseases, hormone or enzyme deficiencies, or tumors.

Glucose, a form of sugar, is an important fuel for your body. Carbohydrates are the main dietary sources of glucose. Rice, potatoes, bread, tortillas, cereal, milk, fruit, and sweets are all carbohydrate-rich foods.

After a meal, glucose molecules are absorbed into your bloodstream and carried to the cells, where they are used for energy. Insulin, a hormone produced by your pancreas, helps glucose enter cells. If you take in more glucose than your body needs at the time, your body stores the extra glucose in your liver and muscles in a form called glycogen. Your body can use the stored glucose whenever it is needed for energy between meals. Extra glucose can also be converted to fat and stored in fat cells.

When blood glucose begins to fall, glucagon, another hormone produced by the pancreas, signals the liver to break down glycogen and release glucose, causing blood glucose levels to rise toward a normal level. If you have diabetes, this glucagon response to hypoglycemia may be impaired, making it harder for your glucose levels to return to the normal range.

The key to avoiding complications with diabetes is to manage blood glucose levels judiciously.  Long-term complications of diabetes are very serious, diminish quality of life, and can take years off your life span.  But long-term problems don't develop magically on their own, they happen slowly over time when daily care is mismanaged.  This is one of the reasons why so many health care professionals are advocates of tight diabetes control.

What are normal glucose ranges?
American Diabetes Association Guidelines

Glucose levels are measured in either:

  • Milligrams per deciliter (mg/dL), in the United States and other countries (Myanmar, Liberia) that do not yet use the International or "Metric" System of measurement, or
  • Millimoles per liter (mmol/L)

The following general guidelines for normal blood glucose ranges in nondiabetics* are from the American Diabetes Association. However, there are variations to these guidelines.  For example, young children, those who are newly diagnosed, or are beginning insulin pump therapy may have slightly different target ranges.

Morning Fasting Blood Glucose

Fasting Glucose Ranges


From 70 to 99 mg/dL, or
3.9 to 5.5. mmol/L

Normal glucose tolerance, not diabetic

From 100 to 125 mg/dL, or
5.6 to 6.9 mmol/L

Impaired fasting glucose (IGF) or Pre-diabetes

126 mg/dL or higher, or
7.0 or higher


Normal and Target Blood Glucose Ranges in mg/dL for Diabetics

The American Diabetes Association sets certain guidelines for normal and abnormal blood glucose levels (appearing at the bottom of this article).  However, as a person with diabetes, your doctor may set different ranges for you.  Young children may have slightly higher target ranges than stable adults.  And those starting out on insulin pump therapy or are newly diagnosed with diabetes may initially have higher target ranges to help avoid hypoglycemia during the initial phase of insulin pumping.

The following chart takes into consideration some of the possibilities that may alter target ranges.  The ranges given are intended for general purposes only and not as a diagnostic tool, or, for you to change your own diabetes care plan.  It is important that you know and understand the target ranges that your doctor sets specifically for managing your own diabetes.

Normal and Target Blood Glucose Ranges in mg/dL for Diabetics

Time of Day


Your doctor may set different ranges for you. USE THE TARGET RANGES YOUR

Notes for Diabetics Only
Your doctor will give you instructions tailored to your own medical needs.  

Morning (Fasting)


90-130 (adults) 90-140 (children) Morning highs may be from the Dawn Effect or the Somogyi Effect.
Before Meals



90-130 adults & older children

100-140 children

"Before meals" means 2-4 hours after last meal was eaten.  For those on rapid insulin only (pumps), generally by 2 hours you should be in, or close to, target range.  Those on shot therapy may not be in range until about 4 hours after their last meal.
2-4 Hours After Meals


Less than 180 but high enough that hypoglycemia won't result from any "onboard" insulin if testing at only 1-2 hours.

Pumpers typically come into target range faster than those on shot therapy (assuming both have given the correct amount of insulin).  Ask your doctor when you should test (2 or 4 hours after a meal)

Before Bedtime


Adults, usually 140-160

Children may have a higher pre-bedtime ranges than adults, up to 180

Have a pre-bedtime snack to help avoid nighttime lows. Note: high-fat snacks late in the evening can cause hyperglycemia (high BG) during the night.

(low blood glucose)

70 or lower

70 or lower

Newly diagnosed, and young children often have higher BG target for hypoglycemia (80-100); infants even higher.

Treat hypoglycemia anytime BG is 70 or lower. Newly diagnosed may be instructed to treat at 100. Stable, but young children may be advised to treat at 80-90. Bear in mind that 100 is fine 4 hours after eating but 100 would be too low only 1 hour after insulin.  Be sure to ask your doctor WHEN (how long after insulin) to treat for hypoglycemia and not just by the BG reading alone.
(high blood glucose)
200 or higher may indicate diabetes

Over 180, 2-4 hours after a meal (2-4 for pumpers, 4 hours for those on shot therapy)

Over 140, morning fasting

Test urine for ketones when blood glucose is 240 or higher. Call doctor for care instructions when scheduled BG reading is over 240 more than twice in one day.

BG = blood glucose

(1) People that are newly diagnosed or just beginning a new type of therapy (such as insulin pumping or going from conventional insulin therapy to intensive insulin therapy) may have slightly higher target ranges set for a certain period of time.  This is done to help avoid dangerous episodes of hypoglycemia (low blood glucose) while medication dose or method of delivery is being adjusted.  Be sure to keep in close contact with your physician whenever your diabetes care plan changes.

Glucose levels vary before and after meals, at various times of day, as well as throughout the night in persons with diabetes as well as in non-diabetics.  It is therefore, important that you understand what target and ranges your doctor sets for you.  If you have trouble meeting your target blood glucose levels you may need to make changes in your diabetes care plan. Call your doctor to learn what adjustments are appropriate for your individual needs.


Common Causes of Hypoglycemia

Causes Related to Diabetes: Missing snacks or meals, eating too little food, taking too much insulin, too much activity, side effects of medications taken, or a combination of these things.

"Stacking" or "piggybacking" insulin is a common cause of hypoglycemia especially in newly diagnosed patients or young children who are unstable or more sensitive to insulin at certain times of the day than at others.  Piggybacking or stacking, simply means giving insulin for correction or food before the previous insulin (on board insulin) is used up resulting in too much insulin in the body.

Another cause for hypoglycemia, especially in young children is excitement.  Studies indicate that children experience more frequent episodes of hypoglycemia around holidays and birthdays than the do at other time.

Another factor that can contribute to hypoglycemia in newly diagnosed patients is when they are "honeymooning" (transient diabetes).  This simply means that the pancreas has not completely shut down yet and from time-to-time will produce some insulin.  See "Honeymooning."

See "Insulin Shock" for more information about hypoglycemia related to taking too much insulin.

Causes Unrelated to Diabetes may include morning fasting hypoglycemia (an indication that there may be an underlying medical problems, and reactive hypoglycemia.


Side Effect of Certain Medications

Hypoglycemia can occur in people with diabetes who take certain medications to keep their blood glucose levels in control. Usually hypoglycemia is mild and can easily be treated by eating or drinking something with carbohydrate. But left untreated, hypoglycemia can lead to loss of consciousness. Although hypoglycemia can happen suddenly, it can usually be treated quickly, bringing your blood glucose level back to normal.

In people taking certain blood-glucose lowering medications, or insulin-sensitizing drugs, blood glucose can fall too low for a number of reasons:

  • Meals or snacks that are too small, delayed, or skipped

  • Some diabetes medications, including sulfonylureas and meglitinides (Alpha-glucosidase inhibitors, biguanides, and thiazolidinediones alone should not cause hypoglycemia but can when used with other diabetes medicines.)
  • Too much Insulin, can result in "insulin shock."  (Read more about this type of hypoglycemia in our section on "Insulin Shock.")
  • Bathing or using a hot tub or sauna.  


Insulin Pumps

If you are on an insulin pump, try to avoid changing out your canula site just before bed time.  New sites can often be more sensitive to insulin, or, if you hit scar tissues, may be less sensitive.  You should always check your blood glucose 1-2 hours after changing your site.  


Bathing, Hot Tubs and Saunas

Another cause for hypoglycemia can be attributed to taking baths or using hot tubs and saunas.  The warmth of the water will increase your insulin sensitivity and result in low blood glucose levels.  It is important to time your shots so that bathing will not alter your sensitivity just before you go to bed.  See "Insulin Reactions" for a guidelines on when it is safe to bath after injecting insulin.

More Information About Hypoglycemia

People with diabetes
Symptoms of Hypoglycemia in Diabetes
Treatment of Hypoglycemia in Diabetes
Prevention of Hypoglycemia in Diabetes
Printable Hypoglycemia Guides
Normal Blood Glucose Ranges
Normal and Target Blood Glucose Ranges in mg/dL for Diabetics

People that do not have diabetes
Hypoglycemia in People Who Do Not Have Diabetes
Symptoms of Non-Diabetes Related Hypoglycemia
Reactive Hypoglycemia
Fasting Hypoglycemia
Conditions Occurring in Childhood and Infancy

Related Information
Insulin Shock
Diabetic Seizures and Coma from Hypoglycemia 
Shot Therapy
Insulin Pump Therapy
Types of Insulin
Tips from Others Living With Diabetes
Lifestyle Changes
Diets for Diabetes and Hypoglycemia



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Page Updated 03/08/2006